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FXYD6 is a novel regulator of Na,K-ATPase expressed in the inner ear.
J Biol Chem. 2007 Mar 09; 282(10):7450-6.JB

Abstract

The exquisite sensitivity of the cochlea, which mediates the transduction of sound waves into nerve impulses, depends on the endolymph ionic composition and the endocochlear potential. A key protein in the maintenance of the electrochemical composition of the endolymph is the Na,K-ATPase. In this study, we have looked for the presence in the rat inner ear of members of the FXYD protein family, recently identified as tissue-specific modulators of Na,K-ATPase. Only FXYD6 is detected at the protein level. FXYD6 is expressed in various epithelial cells bordering the endolymph space and in the auditory neurons. FXYD6 co-localizes with Na,K-ATPase in the stria vascularis and can be co-immunoprecipitated with Na,K-ATPase. After expression in Xenopus oocytes, FXYD6 associates with Na,K-ATPase alpha1-beta1 and alpha1-beta2 isozymes, which are preferentially expressed in different regions of the inner ear and also with gastric and non-gastric H,K-ATPases. The apparent K(+) and Na(+) affinities of alpha1-beta1 and alpha1-beta2 isozymes are different. Association of FXYD6 with Na,K-ATPase alpha1-beta1 isozymes slightly decreases their apparent K(+) affinity and significantly decreases their apparent Na(+) affinity. On the other hand, association with alpha1-beta2 isozymes increases their apparent K(+) and Na(+) affinity. The effects of FXYD6 on the apparent Na(+) affinity of Na,K-ATPase and the voltage dependence of its K(+) effect are distinct from other FXYD proteins. In conclusion, this study defines the last FXYD protein of unknown function as a modulator of Na,K-ATPase. Among FXYD protein, FXYD6 is unique in its expression in the inner ear, suggesting a role in endolymph composition.

Authors+Show Affiliations

Department of Pharmacology and Toxicology, University of Lausanne, Rue du Bugnon 27, 1005 Lausanne, Switzerland.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17209044

Citation

Delprat, Benjamin, et al. "FXYD6 Is a Novel Regulator of Na,K-ATPase Expressed in the Inner Ear." The Journal of Biological Chemistry, vol. 282, no. 10, 2007, pp. 7450-6.
Delprat B, Schaer D, Roy S, et al. FXYD6 is a novel regulator of Na,K-ATPase expressed in the inner ear. J Biol Chem. 2007;282(10):7450-6.
Delprat, B., Schaer, D., Roy, S., Wang, J., Puel, J. L., & Geering, K. (2007). FXYD6 is a novel regulator of Na,K-ATPase expressed in the inner ear. The Journal of Biological Chemistry, 282(10), 7450-6.
Delprat B, et al. FXYD6 Is a Novel Regulator of Na,K-ATPase Expressed in the Inner Ear. J Biol Chem. 2007 Mar 9;282(10):7450-6. PubMed PMID: 17209044.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - FXYD6 is a novel regulator of Na,K-ATPase expressed in the inner ear. AU - Delprat,Benjamin, AU - Schaer,Danièle, AU - Roy,Sophie, AU - Wang,Jing, AU - Puel,Jean-Luc, AU - Geering,Käthi, Y1 - 2007/01/05/ PY - 2007/1/9/pubmed PY - 2007/4/17/medline PY - 2007/1/9/entrez SP - 7450 EP - 6 JF - The Journal of biological chemistry JO - J. Biol. Chem. VL - 282 IS - 10 N2 - The exquisite sensitivity of the cochlea, which mediates the transduction of sound waves into nerve impulses, depends on the endolymph ionic composition and the endocochlear potential. A key protein in the maintenance of the electrochemical composition of the endolymph is the Na,K-ATPase. In this study, we have looked for the presence in the rat inner ear of members of the FXYD protein family, recently identified as tissue-specific modulators of Na,K-ATPase. Only FXYD6 is detected at the protein level. FXYD6 is expressed in various epithelial cells bordering the endolymph space and in the auditory neurons. FXYD6 co-localizes with Na,K-ATPase in the stria vascularis and can be co-immunoprecipitated with Na,K-ATPase. After expression in Xenopus oocytes, FXYD6 associates with Na,K-ATPase alpha1-beta1 and alpha1-beta2 isozymes, which are preferentially expressed in different regions of the inner ear and also with gastric and non-gastric H,K-ATPases. The apparent K(+) and Na(+) affinities of alpha1-beta1 and alpha1-beta2 isozymes are different. Association of FXYD6 with Na,K-ATPase alpha1-beta1 isozymes slightly decreases their apparent K(+) affinity and significantly decreases their apparent Na(+) affinity. On the other hand, association with alpha1-beta2 isozymes increases their apparent K(+) and Na(+) affinity. The effects of FXYD6 on the apparent Na(+) affinity of Na,K-ATPase and the voltage dependence of its K(+) effect are distinct from other FXYD proteins. In conclusion, this study defines the last FXYD protein of unknown function as a modulator of Na,K-ATPase. Among FXYD protein, FXYD6 is unique in its expression in the inner ear, suggesting a role in endolymph composition. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/17209044/FXYD6_is_a_novel_regulator_of_NaK_ATPase_expressed_in_the_inner_ear_ L2 - http://www.jbc.org/cgi/pmidlookup?view=long&pmid=17209044 DB - PRIME DP - Unbound Medicine ER -