GENOMIC ORGANIZATION OF THE GENE FOR PIG ZONA-PELLUCIDA GLYCOPROTEIN ZP1 AND ITS EXPRESSION IN MAMMALIAN-CELLS

The pig zona pellucida (pZP) is composed of glycoproteins pZP1, pZP3 a lpha and pZP3 beta. Previously, we showed that pZP1 was proteolyticall y cleaved into two components (pZP4 and pZP2), and suggested that pZP1 was a homologue of mouse ZP2. We now report the genomic organization of pZP1 gene, and expression of the recombinant protein in mammalian c ells. Two genomic clones, pZP4g and pZP4.1, were isolated by screening the pig genomic library with an already cloned cDNA encoding pZP4 as a probe. These clones covered 25 kb of the genome, including the entir e pZP1 locus. The pig ZP1 genome consists of 18 exons and 17 introns. For production of the recombinant proteins of pZP1, a minigene contain ing a genomic fragment covering exon 6 to exon 17 was constructed and cloned into the expression vector, pBCMGS-neo. Mammalian cell lines, C HO (for stable expression) and 293T (for transient expression), transf ected with the plasmid construct synthesized pZP1 recombinant proteins , probably as a membrane-bound protein.