IMMUNOCHEMICAL IDENTIFICATION OF THE GLYCINE RECEPTOR CL- CHANNEL IN PORCINE SPERM

Cl- flux is essential for the mammalian sperm acrosome reaction (AR), a required fertilization event involving fusion of sperm head membrane s. Our previous inhibitor studies suggested the involvement of a glyci ne receptor/Cl- channel (GlyR) in the zona pellucida-initiated mammali an sperm AR. Here, using a monoclonal antibody specific for the alpha (48-kDa) and beta (58-kDa) subunits of the rat spinal cord GlyR (mAb G lyR4a), we provide the first direct evidence for GlyR in mammalian spe rm. Immunofluorescence studies with mAb GlyR4a detected immunoreactivi ty on the porcine sperm periacrosomal plasma membrane, a site supporti ng GlyR involvement in the AR. In Western immunoblotting studies, mAb GlyR4a bound specifically to porcine sperm proteins of 49.2 +/- 2.2 kD a and 58.0 +/- 2.7 kDa. This is the first direct demonstration of both alpha and beta subunits of GlyR in a nonnervous system cell. (C) 1996 Academic Press, Inc.