Characterization of progressive changes in ZPC of the vitelline membrane of quail oocyte following oviductal transport.

摘要

One of the 2 major glycoproteins in the inner layer of quail vitelline membrane, formerly called 33-kDa glycoprotein, has been found previously to be homologous to mammalian zona pellucida glycoprotein ZPC. In the present work, quail ZPC was found to have different mobilities during SDS-polyacrylamide gel electrophoresis depending on whether it was obtained from preovulatory follicles or laid eggs. In order to characterize the progressive changes in the molecular size of quail ZPC during oviductaltransport, inner layers isolated from follicles were incubated in vivo in various regions of the oviduct and subjected to western blot analysis with anti-quail ZPC antiserum. The molecular weight of quail ZPC from the inner layer incubated in infundibulum decreased until it exhibited the same electrophoretic mobility as ZPC from laid eggs. A similar reduction in molecular weight was observed after in vitro incubation of the inner layer with extracts of infundibulum. From the comparison of the N-terminalamino acid sequences, it was found that the first 26 residues of quail ZPC in follicular oocytes were missing from the ZPC of laid eggs. The results of lectin blot analysis indicated that modification of oligosaccharide chains occurred during oviductaltransport. These results represent the first description in the avian oviduct of the presence of protease, which is similar to oviductin, a trypsin-like protease involved in the hydrolysis of a major component of the vitelline envelope of amphibian oocytes.