THE GENE ENCODING BOVINE PREGNANCY-ASSOCIATED GLYCOPROTEIN-1, AN INACTIVE MEMBER OF THE ASPARTIC PROTEINASE FAMILY

Bovine pregnancy-associated glycoprotein 1 (bPAG1) is a member of the aspartic proteinase family. It becomes detectable in maternal serum so on after implantation and is produced specifically in the invasive bin ucleate cells of the placenta. As a result of a key mutation within it s catalytic center, bPAG1 appears to be proteolytically inactive. Its gene consists of nine exons (size range 99-281 bp) and eight introns ( 87-1800 bp) organized in a manner very similar to those of proteolytic ally active mammalian aspartic proteinases. The transcription start po int (tsp) is located 53 or 54 bp upstream from the start codon (ATG) a nd 19 bp downstream from a 5'-TATATAA sequence. Southern blot analyses have indicated the presence of two bPAG1 genes. By screening with an antiserum raised against bPAG1, a less common cDNA with 91% sequence i dentity to the bPAG1 transcript has been isolated from a placental cDN A library and presumably represents the second gene. At least eight ot her genes with sequences that hybridize relatively weakly to the bPAG1 probe are present in the bovine genome, Despite the similarities in t he transcribed portion of the genes encoding PAG1, pepsinogen and othe r mammalian aspartic proteinases, the sequences upstream from the rsp of bPAG1 are unique.