Monoclonal antibody against a 52 K sperm surface protein inhibits sperm-zona pellucida interactions in the XXXX .

@entity35 @entity46092
A major regulatory site for species specificity of fertilization in mammals lies at the level of sperm binding to the zona pellucida. This implies a high degree of complementarity between gamete and receptor molecules. These molecules support species-specific interactions between sperm and oocyte that lead to gamete fusion (fertilization). We identified a @entity35 sperm head surface antigen using an IgG1 monoclonal antibody ( @entity46092 ) against @entity35 sperm of epididymis cauda. By electron microscopy the antigen was shown to be present on the plasma membrane surface of the sperm dorsal head. One- and two-dimensional immunoblotting analysis of sperm proteins demonstrated that @entity46092 reacted only with a 52 K molecule with a pI ranging from 6.6 to 7.2. The 52 K protein was first detected in situ by indirect immunofluorescence and showed to be underlining few elongated spermatids in testis. However, when the sperm reached the epididymis caput, the antigen was seen to be expressed on the dorsal surface of spermatozoa head. A similar fluorescence reaction was detected on sperms in the epididymis corpus and cauda. The specific spermatozoa-zona pellucida interaction was inhibited in the presence of monoclonal antibody @entity46092 in a sperm binding assay of in vitro fertilization.
