PRIMARY STRUCTURE OF PREGNANCY ZONE PROTEIN - MOLECULAR-CLONING OF A FULL-LENGTH PZP CDNA CLONE BY THE POLYMERASE CHAIN-REACTION

A full-length cDNA clone of the human pregnancy zone protein (PZP) was cloned from the hepatocellular carcinoma cell line Hep3B. Based on the exon sequences of the PZP gene (Devriendt et al. (1989) Gene 81, 325-334; Marynen et at., unpublished data), primer pairs were designed to amplify six overlapping fragments of the PZP cDNA. The obtained cDNA is 4609 bp long and contains an open reading fram coding for 1482 amino acids, including a signal peptide of 25 amino acid residues. Comparison with the published partial PZP amino acid sequence (Sottrup-Jensen et al. (1984) Proc. Natl. Acad. Sci. USA 81, 7353-7357) and the PZP genomic sequences confirmed the identity as a PZP cDNA. 71% of the corresponding amino acid residues in PZP and human alpha-2-macroglobulin (alpha-2-M) are identical and all cysteine residues are conserved. A typical internal thiol ester site and a bait domain were identified. A Pro / Thr polymorphism was identified at amino acid position 1180, and an A / G nucleotide polymorphism at bp 4097.