Identification of three isozyme proteins of the catalytic subunit of the Na,K-ATPase in rat brain

作者：Osamu Urayama, H Shutt, Kathleen J. Sweadner · 发表于：Journal of Biological Chemistry · 年份：1989 · DOI：10.1016/s0021-9258(18)83179-9 · 被引用次数：211 · 研究领域：Ion Transport and Channel Regulation、Pancreatic function and diabetes、Renal and related cancers

Molecular genetic evidence indicates that there should be three different (Na+ + K+)-stimulated ATPase (Na,K-ATPase) alpha subunit isozymes in the brain where previously only two ("alpha" and "alpha(+)") were resolved as proteins. To detect and identify alpha 1, alpha 2, and alpha 3 isozymes, polypeptides made by cell-free translation (Schneider, J.W., Mercer, R.W., Gilmore-Hebert, M., Utset, M.F., Lai, C., Greene, A., and Benz, E.J., Jr. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 284-288) were analyzed by gel electrophoresis and proteolytic fingerprinting. Synthetic alpha 1 comigrated with tissue alpha 1, while alpha 2 and alpha 3 comigrated with the leading and trailing edges, respectively, of tissue "alpha(+)." Proteolytic fingerprints of newborn rat brain Na,K-ATPase labeled in vivo with L-[35S]methionine indicated the presence of alpha 1 and alpha 3, and a low level of alpha 2. Monoclonal antibodies were characterized by the electrophoretic mobility of their antigens and by their ability to recognize the Na,K-ATPases of kidney, brain, and skeletal muscle. The antibodies were used to assess isozyme expression in the brain. All three isozymes increased in abundance during development from the 18-day fetus to the adult. Small changes were seen in the relative level of expression of alpha 1 and alpha 3 at different developmental ages, while alpha 2 expression increased markedly between the neonate and adult. In adult brain, all three isozymes were found in all brain regions ex...