ISOLATION AND PARTIAL CHARACTERIZATION OF AN OVINE PREGNANCY-ASSOCIATED GLYCOPROTEIN (OPAG)

An ovine Pregnancy-Associated Glycoprotein (oPAG) has been isolated fr om fetal cotyledons by the means of ammonium sulfate precipitations an d different liquid chromatographies. The bovine FAG was used as standa rd and tracer to monitor the oPAG in each step of isolation. Ovine FAG seems to be an heterogeneous group of glycoproteins of molecular mass ranging from 47 to 67 kD. Molecular cloning of its cDNA revealed that ovine and bovine FAG share 86 % nucleotide sequence identity and both belong to the aspartic proteinase family (greater than or equal to 50 % amino acid sequence identity to pepsin and cathepsins D and E). How ever neither bovine nor ovine PAGs do not appear to be enzymatically a ctive. The oPAG's cDNA codes for a polypeptide of 382 amino acids long that is synthesized by trophoblastic binucleate cells since day 18 po st conception and detected in maternal circulation since day 24 p.c. T he detection of oPAG could be used for early diagnosis of pregnancy an d determination of early embryonic mortality in sheep and other domest ic and wild ruminants.