Abstracts
Résumé
Les protéines FXYD appartiennent à une famille de petites protéines membranaires. Des études récentes suggèrent que six des sept membres de cette famille, FXYD1 (phospholemman), FXYD2 (sous-unité γ de la Na,K-ATPase), FXYD3 (Mat-8), FXYD4 (CHIF), FXYD5 (Ric) et FXYD7, sont des sous-unités auxiliaires de la Na, K-ATPase régulant son activité de manière tissu et isoforme spécifique. Ces résultats soulignent la complexité de la régulation des ions Na+ et K+ par la Na,K-ATPase qui est nécessaire pour assurer les fonctions propres de différents tissus comme la réabsorption du Na+ par le rein, la contraction musculaire et l’excitabilité neuronale. De plus, une mutation dans FXYD2 a été liée à certains cas d’hypomagnésémie, suggérant que des perturbations de la régulation de la Na,K-ATPase par les protéines FXYD seraient impliquées dans des états physiopathologiques. Une meilleure compréhension de ce nouveau mécanisme de régulation de la Na,K-ATPase pourrait nous aider à mieux comprendre son rôle dans les états physiopathologiques. Dans cet article, nous discutons les données les plus récentes sur le rôle des protéines FXYD dans la modulation de la Na, K-ATPase.
Summary
Members of the FXYD protein family are small membrane proteins which are characterized by an FXYD motif, two conserved glycines and a serine residue. FXYD proteins show a tissue-specific distribution. Recent evidence suggests that 6 out of 7 FXYD proteins, FXYD1 (phospholemman), FXYD2 (γ subunit of Na,K-ATPase), FXYD3 (Mat-8), FXYD4 (CHIF), FXYD5 (Ric) and FXYD7 associate with Na,K-ATPase and modulate its transport properties e.g. its Na+ and/or its K+ affinity in a distinct way. These results highlight the complex regulation of Na+ and K+ transport which is necessary to ensure proper tissue functions such as renal Na+-reabsorption, muscle contractility and neuronal excitability. Moreover, mutation of a conserved glycine residue into an arginine residue in FXYD2 has been linked to cases of human hypomagnesemia indicating that dysregulation of Na,K-ATPase by FXYD proteins may be implicated in pathophysiological states. A better characterization of this novel regulatory mechanism of Na,K-ATPase may help to better understand its role in physiological and pathophysiological conditions.
Appendices
Références
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