Characterization of Na+K+-ATPase in bovine sperm

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• 作者：Katie D. Hickey^a ; Mary M. Buhr^a ; ^{mary.buhr@usask.ca}
• 关键词：Sperm ; Na+K+-ATPase ; Head plasma membrane
• 刊名：Theriogenology
• 出版年：2012
• 期刊代码：98_0093691x
• 类别：abs
• 出版时间：15 April, 2012
• 卷：77
• 期：7
• 页码：1369-1380
• 文件大小：1576 K

摘要

Existing as a ubiquitous transmembrane protein, Na⁺K⁺-ATPase affects sperm fertility and capacitation through ion transport and a recently identified signaling function. Functional Na⁺K⁺-ATPase is a dimer of 伪 and 尾 subunits, each with isoforms (four and three, respectively). Since specific isoform pairings and locations may influence or indicate function, the objective of this study was to identify and localize subunits of Na⁺K⁺-ATPase in fresh bull sperm by immunoblotting and immunocytochemistry using antibodies against 伪1 and 3, and all 尾 isoforms. Relative quantity of Na⁺K⁺-ATPase in head plasma membranes (HPM's) from sperm of different bulls was determined by densitometry of immunoblot bands, and compared to bovine kidney. Sperm and kidney specifically bound all antibodies at kDa equivalent to commercial controls, and to additional lower kDa bands in HPM. Immunofluorescence of intact sperm confirmed that all isoforms were present in the head region of sperm and that 伪3 was also uniformly distributed post-equatorially. Permeabilization exposing internal membranes typically resulted in an increase in fluorescence, indicating that some antibody binding sites were present on the inner surface of the HPM or the acrosomal membrane. Deglycosylation of 尾1 reduced the kDa of bands in sperm, rat brain and kidney, with the kDa of the deglycosylated bands differing among tissues. Two-dimensional blots of 尾1 revealed three distinct spots. Based on the unique quantity, location and structure Na⁺K⁺-ATPase subunits in sperm, we inferred that this protein has unique functions in sperm.