Distribution of 105-kDa sperm unique antigen on goat epididymal mature spermatozoa

The sperm surface antigens are organized into topographic domains, specifically formed into the membrane during the sperm maturation in the epididymis. The present study was directed to determine the distribution of 105 KD sperm membrane antigen (SMA2) into the cell by affinity purified antibody, generated by 105 KD sperm antigen. The cytoimmunofluorescence study of the integrated sperm cell reveal that the antigen is localized in the anterior head overlying the acrosome. On immunoblotting of isolated head and flagellum polypeptides it has been demonstrated that this antigen is selectively present in the head membrane and absent in the flagellum. Because of its selective presence in the anterior head membrane overlying the region of acrosome on mature spermatozoa, the 105 KD sperm unique glyco-antigen may have a role in events leading to sperm-egg recognition. It is a first report of a high molecular mass membrane antigen being localized in the anterior head membrane of goat mature epididymal spermatozoa.