1: J Bioenerg Biomembr. 2005 Dec;37(6):387-92.


Function of FXYD proteins, regulators of Na, K-ATPase.

Geering K.

Department of Pharmacology and Toxicology, University of Lausanne, Rue du Bugnon 27, CH-1005, Lausanne, Switzerland. kaethi.geering@unil.ch

In this short review, we summarize our work on the role of members of the FXYD protein family as tissue-specific modulators of Na, K-ATPase. FXYD1 or phospholemman, mainly expressed in heart and skeletal muscle increases the apparent affinity for intracellular Na(+) of Na, K-ATPase and may thus be important for appropriate muscle contractility. FXYD2 or gamma subunit and FXYD4 or CHIF modulate the apparent affinity for Na(+) of Na, K-ATPase in an opposite way, adapted to the physiological needs of Na(+) reabsorption in different segments of the renal tubule. FXYD3 expressed in stomach, colon, and numerous tumors also modulates the transport properties of Na, K-ATPase but it has a lower specificity of association than other FXYD proteins and an unusual membrane topology. Finally, FXYD7 is exclusively expressed in the brain and decreases the apparent affinity for extracellular K(+), which may be essential for proper neuronal excitability.

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

PMID: 16691470 [PubMed - indexed for MEDLINE]

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2: Neurochem Res. 2001 Sep;26(8-9):971-8.


Endogenous digitalis-like Na+, K+-ATPase inhibitors, and brain function.

Lichtstein D, Rosen H.

Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel. david@md2.huji.ac.il

Digitalis-like compounds are recently identified steroids synthesized by the adrenal gland, which resemble the structure of plant cardiac glycosides. These compounds, like the plant steroids, bind to and inhibit the activity of the Na+, K+-ATPase. The possible function of the endogenous digitalis-like compounds has to be evaluated in view of the presence of different isoforms of the Na+, K+-ATPase, which differ in their sensitivity to digitalis. This review focuses on recent published data on the Na+, K+-ATPase inhibitors, the digitalis-like compounds, regarding their structure, biosynthesis and secretion from the adrenal gland, physiological role and pathological implications in diseases such as hypertension and depression. Emphasis is given to studies describing the involvement of these compounds in brain function.

Publication Types:
Review

PMID: 11699949 [PubMed - indexed for MEDLINE]

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3: Nippon Rinsho. 1996 Mar;54(3):586-94.


[Na, K-ATPase--its structure, function and intracellular transport]

[Article in Japanese]

Omori K, Matsuda H.

Department of Physiology, Kansai Medical University, Japan.

Na, K-ATPase is an integral plasma membrane protein and plays essential roles such as maintaining sodium and potassium ion gradients across the plasma membrane. The enzyme consists of the alpha and the beta subunits with the stoichiometry of one to one. Three alpha subunit and two beta subunit isoforms have been detected in animal cells with the tissue-specific expression of both subunits. Recent advances in molecular biological studies on the Na, K-ATPase enable us to understand the structure-function relationships and mechanisms of intracellular transport of the enzyme. In this article we review the findings deduced from these studies, especially on the assembly and transport to the plasma membrane of the alpha and beta subunits.

Publication Types:
English Abstract
Review

PMID: 8904209 [PubMed - indexed for MEDLINE]

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4: Nauchnye Doki Vyss Shkoly Biol Nauki. 1990;(6):120-31.


[Concepts of the oligomeric structure and function of Na, K-ATPase based on the results of studying ligand binding and of determining the size of the molecular target]

[Article in Russian]

Norby JG.

This review is devoted to the discussion of the sizes and molecular structure of the minimal functional unit of Na, K-ATPase. Special attention is paid to the data obtained by radiation inactivation method and studies on ligand binding. The model for the stepwise radiation inactivation of Na, K-ATPase is proposed. The conclusion is drawn that Na, K-ATPase has a dimeric structure, the interactions between its alpha-subunits stabilize the quaternary structure of the pump. Functionally, each alpha-subunit in a stabilized structure possesses a full hydrolytic activity.

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

PMID: 2169909 [PubMed - indexed for MEDLINE]

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5: Tanpakushitsu Kakusan Koso. 1983 Oct;28(11):1201-17.


[Function and purification of Na+, K+-ATPase]

[Article in Japanese]

Hayashi Y.

Publication Types:
Review

PMID: 6318267 [PubMed - indexed for MEDLINE]

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6: Mol Cell Biochem. 1982 Apr 2;43(3):129-43.


Na+, K+-ATPase: relation of conformational transitions to function.

Askari A.

In its native environment, Na+, K+-ATPase of the plasma membrane is an oligomer consisting of two or more of each of two major subunits. Na+ and K+ move across the membrane through the channels that exist between the catalytic subunits of this oligomer. Two distinct ligand-induced conformational transitions (one due to the binding of K+ and ATP to the enzyme, and the other resulting from the phosphorylation of the enzyme in the presence of Na+ and ATP) cause changes in the geometries of the intersubunit channels, and provide the necessary energy-linked gating mechanisms for the transmembrane movements of ions against electrochemical gradients.

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

PMID: 6283332 [PubMed - indexed for MEDLINE]