The present study was conducted to investigate the presence of hexokinase in human sperm cell, its subcellular localization, its modulation and role in capacitation/acrosome reaction, and tyrosine kinase activity, if any. These studies were conducted using antibodies (Ab) raised against rat brain hexokinase (type I isozyme) that have significant cross-reaction with various human tissue hexokinases and neutralize the catalytic activity of the enzyme. Hexokinase Ab reacted with acrosomal, mid-piece and tail regions of methanol- fixed (~70-80%) and live (~35-52%) sperm in the indirect immunofluorescence technique (IFT) and the immunobead binding technique (IBT), respectively. Hexokinase Ab specifically recognized a band of 116 kDa on the Western blot of detergent-solubilized human sperm preparation that was different from the 95-kDa phosphotyrosine protein. Hexokinase Ab caused a significant (P < 0.01 to < 0.001) and concentration-dependent inhibition of human sperm penetration of zona-free hamster oocytes in the sperm penetration assay (SPA). These data indicate that the hexokinase of 116-kDa molecular weight is present in acrosomal, mid-piece, and tail regions of human sperm. The sperm hexokinase is a glycoprotein that is different from the 95-kDa phosphotyrosine protein and is not phosphorylated at tyrosine residues; however, its antibodies cause agglutination and a concentration-dependent inhibition of fertilizing capacity of human sperm.
|Journal||Journal of Andrology|
|Publication status||Published - 1 Mar 1996|
- human sperm