Function of FXYD proteins, regulators of Na, K-ATPase.
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.
Geering
Käthi
K
Department of Pharmacology and Toxicology, University of Lausanne, Rue du Bugnon 27, CH-1005, Lausanne, Switzerland. kaethi.geering@unil.ch
D000818:Animals; D006706:Homeostasis; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D009928:Organ Specificity; D010750:Phosphoproteins; D015221:Potassium Channels; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology*
C451410:FXYD5 protein, human; C094337:Fxyd4 protein, rat; C462940:Fxyd7 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D015221:Potassium Channels; C069141:phospholemman; C416502:FXYD2 protein, human; D000254:Sodium-Potassium-Exchanging ATPase