MOLECULAR-CLONING, STRUCTURAL-ANALYSIS, AND EXPRESSION OF CARP ZP3 GENE

Two types of cDNAs coding for a major component of carp egg membrane w ere clones from a carp ovarian cDNA library. They encode polypeptides of 422-424 amino acid residues whose sequences are homologous to those of medaka and mammalian ZP3. Similar to the mammalian ZP3 genes, carp ZP3 gene also consists of eight exons and seven introns. Carp ZP3 gen es are 2.9 kb in length and present in multiple forms. Carp ZP3 is a g lycoprotein of 45 kDa. It was transcribed and translated exclusively i n oocytes, in contrast with medaka ZP3, which was synthesized in liver . The transcription of carp ZP3 starts very early in oogenesis, but tr anslation occurs during vitellogenesis, as it is present in vitellogen ic but not in previtellogenic oocytes. ZP3 content in oocytes increase s as vitellogenesis proceeds. (C) 1996 Wiley-Liss, Inc.