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Actin Function
Published by Anonymous on 2007/9/28 (2069 reads)
1: Histol Histopathol. 2007 Sep;22(9):1051-5.


The function of actin in gene transcription.

Obrdlik A, Kukalev A, Percipalle P.

Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, Stockholm, Sweden.

Recent developments in the field of gene transcription regulation have unfolded a key role for actin as an important co-factor for all three eukaryotic RNA polymerases. In this review article we discuss the latest findings on actin in transcription of protein-coding and ribosomal genes, in complex with specific hnRNP proteins and a form of myosin 1beta which is entirely localized to the cell nucleus. Based on these recent studies, we propose a general model where actin may function in basal gene transcription as an allosteric regulator, to recruit transcriptional co-activators on active genes. A future challenge will be the identification of the polymerization state of actin in gene transcription and how it is mechanistically regulated.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 17523083 [PubMed - indexed for MEDLINE]

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2: Annu Rev Biochem. 2007;76:593-627.


Mechanism and function of formins in the control of actin assembly.

Goode BL, Eck MJ.

Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA. goode@brandeis.edu

Formins are a widely expressed family of proteins that govern cell shape, adhesion, cytokinesis, and morphogenesis by remodeling the actin and microtubule cytoskeletons. These large multidomain proteins associate with a variety of other cellular factors and directly nucleate actin polymerization through a novel mechanism. The signature formin homology 2 (FH2) domain initiates filament assembly and remains persistently associated with the fast-growing barbed end, enabling rapid insertion of actin subunits while protecting the end from capping proteins. On the basis of structural and mechanistic work, an integrated model is presented for FH2 processive motion. The adjacent FH1 domain recruits profilin-actin complexes and accelerates filament elongation. The most predominantly expressed formins in animals and fungi are autoinhibited through intramolecular interactions and appear to be activated by Rho GTPases and additional factors. Other classes of formins lack the autoinhibitory and/or Rho-binding domains and thus are likely to be controlled by alternative mechanisms.

Publication Types:
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Review

PMID: 17373907 [PubMed - indexed for MEDLINE]

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3: Int Rev Cytol. 2006;252:219-64.


Organization and function of the actin cytoskeleton in developing root cells.

Blancaflor EB, Wang YS, Motes CM.

Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401, USA.

The actin cytoskeleton is a highly dynamic structure, which mediates various cellular functions in large part through accessory proteins that tilt the balance between monomeric G-actin and filamentous actin (F-actin) or by facilitating interactions between actin and the plasma membrane, microtubules, and other organelles. Roots have become an attractive model to study actin in plant development because of their simple anatomy and accessibility of some root cell types such as root hairs for microscopic analyses. Roots also exhibit a remarkable developmental plasticity and possess a delicate sensory system that is easily manipulated, so that one can design experiments addressing a range of important biological questions. Many facets of root development can be regulated by the diverse actin network found in the various root developmental regions. Various molecules impinge on this actin scaffold to define how a particular root cell type grows or responds to a specific environmental signal. Although advances in genomics are leading the way toward elucidating actin function in roots, more significant strides will be realized when such tools are combined with improved methodologies for accurately depicting how actin is organized in plant cells.

Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Review

PMID: 16984819 [PubMed - indexed for MEDLINE]

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4: Microbiol Mol Biol Rev. 2006 Sep;70(3):605-45.


The yeast actin cytoskeleton: from cellular function to biochemical mechanism.

Moseley JB, Goode BL.

Department of Biology and The Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454, USA.

All cells undergo rapid remodeling of their actin networks to regulate such critical processes as endocytosis, cytokinesis, cell polarity, and cell morphogenesis. These events are driven by the coordinated activities of a set of 20 to 30 highly conserved actin-associated proteins, in addition to many cell-specific actin-associated proteins and numerous upstream signaling molecules. The combined activities of these factors control with exquisite precision the spatial and temporal assembly of actin structures and ensure dynamic turnover of actin structures such that cells can rapidly alter their cytoskeletons in response to internal and external cues. One of the most exciting principles to emerge from the last decade of research on actin is that the assembly of architecturally diverse actin structures is governed by highly conserved machinery and mechanisms. With this realization, it has become apparent that pioneering efforts in budding yeast have contributed substantially to defining the universal mechanisms regulating actin dynamics in eukaryotes. In this review, we first describe the filamentous actin structures found in Saccharomyces cerevisiae (patches, cables, and rings) and their physiological functions, and then we discuss in detail the specific roles of actin-associated proteins and their biochemical mechanisms of action.

Publication Types:
Research Support, N.I.H., Extramural
Review

PMID: 16959963 [PubMed - indexed for MEDLINE]

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5: Tanpakushitsu Kakusan Koso. 2006 May;51(6 Suppl):505-10.


[Structure and function of actin]

[Article in Japanese]

Nakagawa H, Miyamoto S.

Publication Types:
Review

PMID: 16719304 [PubMed - indexed for MEDLINE]

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6: Tanpakushitsu Kakusan Koso. 2006 Apr;51(4):350-6.


[Dynamics and function of actin-binding proteins in excitatory synapses]

[Article in Japanese]

Sekino Y, Shirao T.

yukos@ims.u-tokyo.ac.jp

Publication Types:
Review

PMID: 16613172 [PubMed - indexed for MEDLINE]

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7: Can J Physiol Pharmacol. 2005 Oct;83(10):877-91.


The association of caveolae, actin, and the dystrophin-glycoprotein complex: a role in smooth muscle phenotype and function?

Halayko AJ, Stelmack GL.

Department of Physiology, University of Manitoba, Winnipeg, Canada. ahalayk@cc.umanitoba.ca

Smooth muscle cells exhibit phenotypic and mechanical plasticity. During maturation, signalling pathways controlling actin dynamics modulate contractile apparatus-associated gene transcription and contractile apparatus remodelling resulting from length change. Differentiated myocytes accumulate abundant caveolae that evolve from the structural association of lipid rafts with caveolin-1, a protein with domains that confer unique functional properties. Caveolae and caveolin-1 modulate and participate in receptor-mediated signalling, and thus contribute to functional diversity of phenotypically similar myocytes. In mature smooth muscle, caveolae are partitioned into discrete linear domains aligned with structural proteins that tether actin to the extracellular matrix. Caveolin-1 binds with beta-dystroglycan, a subunit of the dystrophin glycoprotein complex (DGC), and with filamin, an actin binding protein that organizes cortical actin, to which integrins and focal adhesion complexes are anchored. The DGC is linked to the actin cytoskeleton by a dystrophin subunit and is a receptor for extracellular laminin. Thus, caveolae and caveolin-associated signalling proteins and receptors are linked via structural proteins to a dynamic filamentous actin network. Despite development of transgenic models to investigate caveolins and membrane-associated actin-linking proteins in skeletal and cardiac muscle function, only superficial understanding of this association in smooth muscle phenotype and function has emerged.

Publication Types:
Review

PMID: 16333360 [PubMed - indexed for MEDLINE]

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8: Annu Rev Neurosci. 2005;28:25-55.


The actin cytoskeleton: integrating form and function at the synapse.

Dillon C, Goda Y.

MRC Cell Biology Unit and Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom. christian.dillon@ucl.ac.uk

Synapses are highly specialized intercellular junctions that mediate the transmission of information between axons and target cells. A fundamental property of synapses is their ability to modify the efficacy of synaptic communication through various forms of synaptic plasticity. Recent developments in imaging techniques have revealed that synapses exhibit a high degree of morphological plasticity under basal conditions and also in response to neuronal activity that induces alterations in synaptic strength. The underlying molecular basis for this morphological plasticity has attracted much attention, yet its functional significance to the mechanisms of synaptic transmission and synaptic plasticity remains elusive. These morphological changes ultimately require the dynamic actin cytoskeleton, which is the major structural component of synapses. Delineating the physiological roles of the actin cytoskeleton in supporting synaptic transmission and synaptic plasticity, therefore, paves the way for gaining molecular insights into when and how synaptic machineries couple synapse form and function.

Publication Types:
Review

PMID: 16029114 [PubMed - indexed for MEDLINE]

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9: Trends Cell Biol. 2005 Jun;15(6):333-41.


Tropomyosin isoforms: divining rods for actin cytoskeleton function.

Gunning PW, Schevzov G, Kee AJ, Hardeman EC.

Oncology Research Unit, The Children's Hospital at Westmead, Locked Bag 4001, Westmead NSW 2145, Australia. peterg3@chw.edu.au

Actin filament functional diversity is paralleled by variation in the composition of isoforms of tropomyosin in these filaments. Although the role of tropomyosin is well understood in skeletal muscle, where it regulates the actin-myosin interaction, its role in the cytoskeleton has been obscure. The intracellular sorting of tropomyosin isoforms indicated a role in spatial specialization of actin filament function. Genetic manipulation and protein chemistry studies have confirmed that these isoforms are functionally distinct. Tropomyosins differ in their recruitment of myosin motors and their interaction with actin filament regulators such as ADF-cofilin. Tropomyosin isoforms have therefore provided a powerful mechanism to diversify actin filament function in different intracellular compartments.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 15953552 [PubMed - indexed for MEDLINE]

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10: Sheng Li Ke Xue Jin Zhan. 2004 Oct;35(4):306-10.


[Structure, function and modulation of actin-related protein 2/3 complex]

[Article in Chinese]

Gong XW, Jiang Y.

Department of Pathophysiology of the First Military Medical University.

Microfilaments, composed of global actins, involve in many important physiological activities, such as the maintenance of cell shape and cell migration. Actin-related protein 2/3 ( Arp2/3) complex plays a key role in microfilament formation. Actin-related protein 2/3 ( Arp2/3 ) complex which is composed of seven different subunits is subjected to the modulation of many nucleation promoting factors (NPFs) and cooperates with these factors to regulate the actin nucleation. The study of the structure, function and modulation of Arp2/3 complex is important in understanding the mechanism of the formation of microfilament and the interaction between cytoskeleton and signaling molecules.

Publication Types:
English Abstract
Research Support, Non-U.S. Gov't
Review

PMID: 15727206 [PubMed - indexed for MEDLINE]

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11: J Urol. 2004 Oct;172(4 Pt 2):1667-72.


Decreased expression of smooth muscle alpha-actin results in decreased contractile function of the mouse bladder.

Zimmerman RA, Tomasek JJ, McRae J, Haaksma CJ, Schwartz RJ, Lin HK, Cowan RL, Jones AN, Kropp BP.

Department of Urology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.

PURPOSE: Smooth muscle alpha-actin (SMalphaA) is an important actin isoform for functional contractility in the mouse bladder. Alterations in the expression of SMalphaA have been associated with a variety of bladder pathological conditions. Recently, a SMalphaA-null mouse was generated and differences in vascular tone and contractility were observed between wild-type and SMalphaA-null mice suggesting alterations in function of vascular smooth muscle. We used SMalphaA-null mice to explore the hypothesis that SMalphaA is necessary for normal bladder function. MATERIALS AND METHODS: Reverse transcriptase polymerase chain reaction, Western blotting and immunohistochemical staining were used to confirm the absence of SMalphaA transcript and protein in the bladder of SMalphaA-null mice. In vitro bladder contractility compared between bladder rings harvested from wild-type and SMalphaA-null mice was determined by force measurement following electrical field stimulation (EFS), and exposure to chemical agonists and antagonists including KCl, carbachol, atropine and tetrodotoxin. Resulting force generation profiles for each tissue and agent were analyzed. RESULTS: There was no detectable SMalphaA transcript and protein expression in the bladder of SMalphaA-null mice. Nine wild-type and 9 SMalphaA-null mice were used in the contractility study. Bladders from SMalphaA-null mice generated significantly less force than wild-type mice in response to EFS after KCl. Similarly, bladders from SMalphaA-null mice generated less force than wild-type mice in response to pretreatment EFS, and EFS after carbachol and atropine, although the difference was not significant. Surprisingly, the bladders in SMalphaA-null mice appeared to function normally and showed no gross or histological abnormalities. CONCLUSIONS: SMalphaA appears to be necessary for the bladder to be able to generate normal levels of contractile force. No functional deficits were observed in the bladders of these animals but no stress was placed on these bladders. To our knowledge this study represents the first report to demonstrate the importance of expression of SMalphaA in force generation in the bladder.

Publication Types:
Review

PMID: 15371786 [PubMed - indexed for MEDLINE]

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12: Rev Neurosci. 2003;14(3):233-40.


Regulation of spine morphology and synaptic function by LIMK and the actin cytoskeleton.

Meng Y, Zhang Y, Tregoubov V, Falls DL, Jia Z.

Program in Brain and Behavior, The Hospital For Sick Children, Toronto, Ontario, Canada.

Filamentous actin (F-actin) is highly enriched in the dendritic spine, a specialized postsynaptic structure on which the great majority of the excitatory synapses are formed in the mammalian central nervous system (CNS). The protein kinases of the Lim-kinase (LIMK) family are potent regulators of actin dynamics in many cell types and they are abundantly expressed in the CNS, including the hippocampus. Using a combination of genetic manipulations and electrophysiological recordings in mice, we have demonstrated that LIMK-1 signaling is important in vivo in the regulation of the actin cytoskeleton, spine morphology, and synaptic function, including hippocampal long-term potentiation (LTP), a prominent form of long lasting synaptic plasticity thought to be critical to memory formation. Our results provide strong genetic evidence that LIMK and its substrate ADF/cofilin are involved in spine morphology and synaptic properties and are consistent with the notion that the Rho family small GTPases and the actin cytoskeleton are critical to spine structure and synaptic regulation.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 14513866 [PubMed - indexed for MEDLINE]

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13: Chest. 2003 Mar;123(3 Suppl):392S-8S.


Actin dynamics: a potential integrator of smooth muscle (Dys-)function and contractile apparatus gene expression in asthma. Parker B. Francis lecture.

Solway J, Bellam S, Dowell M, Camoretti-Mercado B, Dulin N, Fernandes D, Halayko A, Kocieniewski P, Kogut P, Lakser O, Liu HW, McCauley J, McConville J, Mitchell R.

Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA. jsolway@medicine.bsd.unichicago.edu

Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review

PMID: 12629000 [PubMed - indexed for MEDLINE]

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14: Annu Rev Genet. 2002;36:455-88. Epub 2002 Jun 11.


Understanding the function of actin-binding proteins through genetic analysis of Drosophila oogenesis.

Hudson AM, Cooley L.

Departments of Genetics Yale University School of Medicine, P.O. Box 208005, New Haven, Connecticut 06520-8005, USA. andrew.hudson@yale.edu

Much of our knowledge of the actin cytoskeleton has been derived from biochemical and cell biological approaches, through which actin-binding proteins have been identified and their in vitro interactions with actin have been characterized. The study of actin-binding proteins (ABPs) in genetic model systems has become increasingly important for validating and extending our understanding of how these proteins function. New ABPs have been identified through genetic screens, and genetic results have informed the interpretation of in vitro experiments. In this review, we describe the molecular and ultrastructural characteristics of the actin cytoskeleton in the Drosophila ovary, and discuss recent genetic analyses of actin-binding proteins that are required for oogenesis.

Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review

PMID: 12429700 [PubMed - indexed for MEDLINE]

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15: Results Probl Cell Differ. 2001;32:103-21.


Actin structure function relationships revealed by yeast molecular genetics.

Belmont LD, Drubin DG.

Department of Molecular and Cell Biology, 401 Barker Hall, University of California, Berkeley, California 94720-3202, USA.

Publication Types:
Review

PMID: 11131826 [PubMed - indexed for MEDLINE]

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16: Nat Cell Biol. 2000 Oct;2(10):E191-6.


Function of Rho family proteins in actin dynamics during phagocytosis and engulfment.

Chimini G, Chavrier P.

Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, Case 906, 13288 Marseille Cedex 9, France.

Phagocytosis is the uptake of large particles by cells by a mechanism that is based on local rearrangement of the actin microfilament cytoskeleton. In higher organisms, phagocytic cells are essential for host defence against invading pathogens, and phagocytosis contributes to inflammation and the immune response. In addition, engulfment, defined as the phagocytic clearance of cell corpses generated by programmed cell death or apoptosis, has an essential role in tissue homeostasis. Although morphologically distinct phagocytic events can be observed depending on the type of surface receptor engaged, work over the past two years has revealed the essential underlying role of Rho family proteins and their downstream effectors in controlling actin dynamics during phagocytosis.

Publication Types:
Review

PMID: 11025683 [PubMed - indexed for MEDLINE]

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17: Trends Cell Biol. 2000 Mar;10(3):92-7.


Searching for a function for nuclear actin.

Rando OJ, Zhao K, Crabtree GR.

Stanford University Medical School, Stanford, CA 94305, USA.

The abundant cytoskeletal protein actin has numerous cytoplasmic roles. Although there are many reports of the presence of actin in the nucleus, in general they have been discounted as artifactual. However, recent work has begun to provide evidence for important roles for actin in nuclear processes ranging from chromatin remodelling to splicing. In addition, several regulators of actin polymerization are localized to the nucleus or translocate to the nucleus in a regulated manner, suggesting that there is some function of actin in the nucleus that is subject to regulation. This review discusses the evidence for actin in the nucleus and summarizes recent work suggesting that actin or actin-related proteins are involved in the regulation of nuclear processes such as chromatin remodelling.

Publication Types:
Review

PMID: 10675902 [PubMed - indexed for MEDLINE]

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18: Int Rev Cytol. 1997;175:29-90.


The structure, function, and assembly of actin filament bundles.

Furukawa R, Fechheimer M.

Department of Cellular Biology, University of Georgia, Athens 30602, USA.

The cellular organization, function, and molecular composition of selected biological systems with prominent actin filament bundles are reviewed. An overall picture of the great variety of functions served by actin bundles emerges from this overview. A unifying theme is that the actin cross-linking proteins are conserved throughout the eukaryotic kingdom and yet assembled in a variety of combinations to produce actin bundles of differing functions. Mechanisms of actin bundle formation in vitro are considered illustrating the variety of physical and chemical driving forces in this exceedingly complex process. Our limited knowledge regarding the formation of actin filament bundles in vivo is contrasted with the elegant biophysical studies performed in vitro but nonetheless reveals that interactions with membranes, nucleation sites, and other organizational components must contribute to formation of actin bundles in vivo.

Publication Types:
Comparative Study
Research Support, U.S. Gov't, Non-P.H.S.
Review

PMID: 9203356 [PubMed - indexed for MEDLINE]

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19: Curr Opin Hematol. 1994 Jan;1(1):61-8.


Actin polymerization and leukocyte function.

Howard TH, Watts RG.

University of Alabama at Birmingham School of Medicine, USA.

The coordinated remodeling of the filamentous actin-based microfilamentous cytoskeleton via regulated polymerization and depolymerization of globular and filamentous actin is required for polymorphonuclear leukocyte motile functions including locomotion, shape change, phagocytosis, and adhesion. Significant new observations on the structure and function of distinct filamentous actin pools in polymorphonuclear leukocytes, the mechanisms of chemotactic peptide-mediated actin polymerization, the role of filamentous actin in polymorphonuclear shape change in suspension and on a surface, the identification and characterization of rare patients with polymorphonuclear motile defects and actin dysfunctions, and regulation of actin reorganizations by actin regulatory proteins, the phosphorylation or dephosphorylation states of proteins, and the second messengers--the phosphoinositides--were reported in the past year. These observations form the basis for an improved understanding of the cellular and molecular role of actin assembly in polymorphonuclear function and are the subject of this review.

Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review

PMID: 9371261 [PubMed - indexed for MEDLINE]

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20: Annu Rev Cell Biol. 1994;10:207-49.


Structure of actin binding proteins: insights about function at atomic resolution.

Pollard TD, Almo S, Quirk S, Vinson V, Lattman EE.

Department of Cell Biology and Anatomy, Johns Hopkins Medical School, Baltimore, Maryland 21205.

Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review

PMID: 7888177 [PubMed - indexed for MEDLINE]

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21: Biochem J. 1993 May 1;291 ( Pt 3):657-71.


Molecular genetics of actin function.

Hennessey ES, Drummond DR, Sparrow JC.

Department of Biology, University of York, U.K.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 8489492 [PubMed - indexed for MEDLINE]

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22: Curr Opin Cell Biol. 1993 Feb;5(1):41-7.


Actin molecular structure and function.

Reisler E.

Department of Chemistry and Biochemistry, University of California, Los Angeles 90024-1570.

The understanding of actin structure and function has been improved by comparing the atomic structure of G-actin, the model of the F-actin structure, and the properties of actin mutants. Several aspects of actin structure have been tested and good progress has been made in mapping its myosin-binding sites. The dynamic properties of actin and genetic evaluation of its cellular function are attracting increasing attention.

Publication Types:
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.
Review

PMID: 8448029 [PubMed - indexed for MEDLINE]

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23: Adv Cancer Res. 1993;62:19-64.


Pathways of Ras function: connections to the actin cytoskeleton.

Prendergast GC, Gibbs JB.

Department of Cancer Research, Merck Research Laboratories, West Point, Pennsylvania 19486.

Publication Types:
Review

PMID: 8109319 [PubMed - indexed for MEDLINE]

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24: Annu Rev Biophys Biomol Struct. 1992;21:49-76.


Structure and function of actin.

Kabsch W, Vandekerckhove J.

Max-Planck-Institut für medizinische Forschung, Abteilung Biophysik, Heidelberg, Germany.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 1388079 [PubMed - indexed for MEDLINE]

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25: Symp Soc Exp Biol. 1992;46:111-29.


Drosophila actin mutants and the study of myofibrillar assembly and function.

Sparrow JC, Drummond DR, Hennessey ES, Clayton JD, Lindegaard FB.

Department of Biology, University of York, U.K.

The use of Drosophila mutations in the indirect flight muscle-specific actin gene, Act88F, to study actin structure/function and its assembly into thin filaments during myofibrillogenesis is described. Mutants with different phenotypic effects are discussed and attempts made to correlate the different properties of the mutants in vivo-myofibrillar structure, actin synthesis, accumulation and stability, heat shock response induction-with properties of the same mutations expressed by in vitro transcription/translation of the cloned actin genes-co-polymerisation, thermostability and protein conformation. Few of the properties show a complete correlation between the different classes of mutants. The nature of the diversity of the mutant effects is discussed. Questions as to how this will help in elucidating the molecular effects of the mutations and the assembly of thin filaments and myofibrils are considered. In addition, the efficacy of the co-polymerisation assay is examined. The post-translational processing of this actin-by N-terminal processing, methylation and ubiquitination-are described. Data is presented that inhibition of the N-terminal processing of actin in vitro affects the ability of the actin to copolymerise, and makes unprocessed actin behave as a capping protein. The possible in vivo importance of this phenomenon is discussed.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 1341030 [PubMed - indexed for MEDLINE]

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26: Bioessays. 1990 Sep;12(9):403-8.


From the structure to the function of villin, an actin-binding protein of the brush border.

Friederich E, Pringault E, Arpin M, Louvard D.

Département de Biologie Moléculaire, Institut Pasteur, Paris.

Villin, a calcium-regulated actin-binding protein, modulates the structure and assembly of actin filaments in vitro. It is organized into three domains, the first two of which are homologous. Villin is mainly produced in epithelial cells that develop a brush border and which are responsible for nutrient uptake. Expression of the villin structural gene is precisely regulated during mouse embryogenesis and is restricted in adults, to certain epithelia of the gastrointestinal and urogenital tracts. The function of villin has been assessed by transfecting CV1 cells with a human cDNA encoding wild-type villin or mutant villin. Synthesis of large amounts of villin in cells which do not normally produce this protein induces the growth of microvilli on the cell surface and the redistribution of F-actin, concomitant with the disappearance of stress fibers. The complete villin sequence is required for the morphogenic effect. These results suggest that villin plays a key role in the morphogenesis of microvilli.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 2256904 [PubMed - indexed for MEDLINE]

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27: Int Rev Cytol. 1989;119:1-56.


Distribution and function of organized concentrations of actin filaments in mammalian spermatogenic cells and Sertoli cells.

Vogl AW.

Department of Anatomy, Faculty of Medicine, University of British Columbia, Vancouver, Canada.

Actin filaments are concentrated in specific regions of spermatogenic cells and Sertoli cells. In spermatogenic cells they occur in intercellular bridges and in the subacrosomal space. In Sertoli cells they are abundant in ectoplasmic specializations and in regions adjacent to tubulobulbar processes of spermatogenic cells. At all of these sites, the filaments are morphologically related to the plasma membrane and+or intercellular membranes, and, as in many other cell types, are arranged in either bundles or networks. In at least two of the locations just indicated (ectoplasmic specializations and intercellular bridges), elements of the ER are closely related to the actin filaments. In tubulobulbar complexes, ER is present but is more distantly related to the filaments. Elements of the ER, when present, may serve a regulatory function. The filaments in ectoplasmic specializations and in regions adjacent to tubulobulbar processes of spermatogenic cells are suspected to be involved with the mechanism by which intercellular junctions are established, maintained, and degraded. In intercellular bridges, actin filaments may serve to reinforce and perhaps regulate the size of the cytoplasmic connections between differentiating germ cells. Filaments in the subacrosomal space may serve as a linking network between the acrosome and nucleus and may also be involved in the capping process. Because of the possibility that the actin filaments discussed before may be related to specific membrane domains involved with intercellular or interorganelle attachment, and that changes in these membrane domains are prerequisite to processes such as sperm release, turnover of the blood-testis barrier, formation of the acrosome, and coordination of spermatogenic cell differentiation, an understanding of exactly how these actin filaments are related to elements in the membrane and how this interaction is controlled is fundamental to our understanding, and perhaps our manipulating, of male fertility. I suspect that working out the molecular organization of these actin filament-containing sites and determining how their organization is controlled will be the major focus of research in this field over the next few years.

Publication Types:
Review

PMID: 2695482 [PubMed - indexed for MEDLINE]

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28: Cell Motil Cytoskeleton. 1989;14(1):35-9.


Actin structure-function relationships in vitro using oligodeoxynucleotide-directed site-specific mutagenesis.

Rubenstein PA, Solomon LR, Solomon T, Gay L.

Department of Biochemistry, University of Iowa College of Medicine, Iowa City 52242.

Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review

PMID: 2684425 [PubMed - indexed for MEDLINE]

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29: Tanpakushitsu Kakusan Koso. 1985 Dec;30(14 Suppl):1590-607.


[Analysis of the promoter function of cellular slime mold actin genes in the cell-free transcription system]

[Article in Japanese]

Iwabuchi M, Takahashi K, Ozaki T, Takiya S.

Publication Types:
Research Support, Non-U.S. Gov't
Review

PMID: 3914662 [PubMed - indexed for MEDLINE]

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30: Cell Motil. 1981;1(4):485-97.


Invited review: the role of nucleotide triphosphate in actin and tubulin assembly and function.

Weisenberg RC.

Both actin and tubulin, the major proteins of the cytoskeleton, bind nucleotide triphosphate (NTP) and exhibit the phenomenon of "polymerization-coupled" NTP hydrolysis. In this report I review the nature of polymerization-coupled NTP hydrolysis, and its possible role in the cellular function of actin and tubulin. Polymerization-coupled hydrolysis may be viewed as simply reflecting differences in the NTPase activity of free subunit as compared to polymer. Making assumptions concerning the values of various rate constants, it is possible to write expressions for the effects of NTP hydrolysis on the kinetics of polymerization. The role of NTP hydrolysis may be viewed in at least three different ways: 1) Hydrolysis alters the kinetics of assembly and disassembly. This leads to a consideration of the role of subunit flow in microtubule and microfilament function. 2) Hydrolysis is an essentially irreversible step that separates the assembly and disassembly reactions. This suggests a role of NTP in the regulation of polymer content during cellular cycles of assembly and disassembly. 3) NTP may allow transient stabilization of intersubunit bonds. This suggests a role of NTP in nucleation and possible regulation of nonequilibrium states of assembly.

Publication Types:
Review

PMID: 6760979 [PubMed - indexed for MEDLINE]

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31: Cell Motil. 1981;1(4):485-97.


Invited review: the role of nucleotide triphosphate in actin and tubulin assembly and function.

Weisenberg RC.

Both actin and tubulin, the major proteins of the cytoskeleton, bind nucleotide triphosphate (NTP) and exhibit the phenomenon of "polymerization-coupled" NTP hydrolysis. In this report I review the nature of polymerization-coupled NTP hydrolysis, and its possible role in the cellular function of actin and tubulin. Polymerization-coupled hydrolysis may be viewed as simply reflecting differences in the NTPase activity of free subunit as compared to polymer. Making assumptions concerning the values of various rate constants, it is possible to write expressions for the effects of NTP hydrolysis on the kinetics of polymerization. The role of NTP hydrolysis may be viewed in at least three different ways: 1) Hydrolysis alters the kinetics of assembly and disassembly. This leads to a consideration of the role of subunit flow in microtubule and microfilament function. 2) Hydrolysis is an essentially irreversible step that separates the assembly and disassembly reactions. This suggests a role of NTP in the regulation of polymer content during cellular cycles of assembly and disassembly. 3) NTP may allow transient stabilization of intersubunit bonds. This suggests a role of NTP in nucleation and possible regulation of nonequilibrium states of assembly.

Publication Types:
Review

PMID: 6756643 [PubMed - indexed for MEDLINE]
 

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