Nature of the proteins which form disulfide bonds during the maturation of rat spermatozoa

Abstract

The proteins which form disulfide bonds during the maturation of rat spermatozoa were studied by comparing the [14C]carboxamidomethylated products between the caput and caudal spermatozoa. The total incorporation of [14C]iodoacetamide into 106 spermatozoa from the caput epididymis was 13.4 nmole, and those from the caudal epididymis was 3.6 nmole. The proteins extractable from the caput and caudal spermatozoa showed no detectable difference in SDS polyacrylamide gel electrophoretic patterns. Similarly, no detectable change was observed when the proteins were extracted and analysed on polyacrylamide gel containing the cationic detergent cetyltrimethyl‐ammoniumbromide (CTAB). However, when the [14C]carboxamidomethy‐lated products were compared, large differences were evident. There were 4 major carboxamidomethylated products on proteins with molecular weights of 32.000; 29.000; 22.000; and 13.000. The 32.000 and 29.000 dalton proteins were carboxamidomethylated about 15 times in the caput over the caudal spermatozoa. The results suggest that these 4 proteins constitute the majority of those which form disulfide bonds during the maturation of rat spermatozoa. The probable origins of those proteins were briefly discussed. Copyright © 1982, Wiley Blackwell. All rights reserved