Identification of a crab gill FXYD2 protein and regulation of crab microsomal Na,K-ATPase activity by mammalian FXYD2 peptide

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• 作者：Elias C.C. Silva ; Douglas C. Masui ; Rosa P. Furriel ; John C. McNamara ; Hector Barrabin ; Helena M. Scofano ; Jonas Perales ; Andr¨¦ Teixeira-Ferreira ; Francisco A. Leone ; Carlos Frederico L. Fontes
• 关键词：Na ; K-ATPase ; FXYD2 peptide ; Gill microsome ; Endogenous kinase ; Phosphorylation ; Euryhaline crab
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：2012
• 出版时间：November, 2012
• 年：2012
• 卷：1818
• 期：11
• 页码：2588-2597
• 全文大小：779 K

文摘

This investigation discloses the recognition of an FXYD2 protein in a microsomal Na,K-ATPase preparation from the posterior gills of the blue crab, Callinectes danae, by a mammalian (rabbit) FXYD2 peptide specific antibody (¦ÃC³³) and MALDI-TOF-TOF mass spectrometry techniques. This is the first demonstration of an invertebrate FXYD2 protein. The addition of exogenous pig FXYD2 peptide to the crab gill microsomal fraction stimulated Na,K-ATPase activity in a dose-dependent manner. Exogenous pig FXYD2 also considerably increased enzyme affinity for K⁺, ATP and NH₄⁺. K_0.5 for Na⁺ was unaffected. Exogenous pig FXYD2 increased the V_max for stimulation of gill Na,K-ATPase activity by Na⁺, K⁺ and ATP, by 30 % to 40 % . The crab gill FXYD2 is phosphorylated by PKA, suggesting a regulatory function similar to that known for the mammalian enzyme. The PKA-phosphorylated pig FXYD2 peptide stimulated the crab gill Na,K-ATPase activity by 80 % , about 2-fold greater than did the non-phosphorylated peptide. Stimulation by the PKC-phosphorylated pig FXYD2 peptide was minimal. These findings confirm the presence of an FXYD2 peptide in the crab gill Na,K-ATPase and demonstrate that this peptide plays an important role in regulating enzyme activity.