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 (γC 33) 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 NH 4+. 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. © 2012 Elsevier B.V.
Silva, E. C. C., Masui, D. C., Furriel, R. P., McNamara, J. C., Barrabin, H., Scofano, H. M., … Fontes, C. F. L. (2012). Identification of a crab gill FXYD2 protein and regulation of crab microsomal Na,K-ATPase activity by mammalian FXYD2 peptide. Biochimica et Biophysica Acta - Biomembranes, 1818(11), 2588–2597. https://doi.org/10.1016/j.bbamem.2012.05.009