CD52 is the 'major maturation-associated' sperm membrane antigen.

The 'major maturation-associated' sperm membrane antigen is the most prominent glycopeptide which appears on the surface of rat spermatozoa during post-testicular sperm maturation. The name describes the fact that its occurrence coincides with the spermatozoa acquiring their major physiological properties of maturation in the distal epididymis. It is shown in this study that this phenomenon is not restricted to the rat. Rather, by immunohistochemical staining, in-situ transcript hybridization and molecular analyses of genomic DNA fragments it is evident that homologous counterparts exist in other mammalian species, including the human. The human homologue is an abundant epididymal gene product that has previously been identified as lymphocyte surface antigen CD52. Thus, following the human standard nomenclature, it seems more appropriate to refer to these molecules as CD52 homologues. Localization of the mRNA for these glycosylphosphatidyl inositol (GPI)-anchored glycopeptides within the epididymal epithelium, and not within the testis, suggests that they may be transferred from epididymal to sperm cell with their GPI-anchor intact.