Three hormonally regulated proteins with mol.wts of 18 500, 19 000 and 23 000 have been shown to associate with the plasma membrane of spermatozoa during maturation in the epididymis. All three proteins showed some alpha-lactalbumin-like activity, suggesting that they may act in concert with epididymal glycosidases and glycosyltransferases to regulate the modification of sugars on membrane-bound glycoproteins.
