Characterization of cDNA encoding novel pregnancy-specific glycoprotein variants.

The human pregnancy-specific glycoprotein (PSG) family consists of eleven closely related molecules mainly synthesized by placental syncytiotrophoblasts and whose function(s) are unknown. They belong to the carcinoembryonic antigen (CEA) family. As a step toward understanding PSG function, we have analysed 84 PSG cDNA clones from a fetal liver library with respect to domain arrangement and PSG identity. Four novel PSG cDNAs derived from the PSG4, PSG7, PSG11, and PSG13 genes were characterized. The PSG11 and PSG13 cDNAs had novel domain arrangements: L-N-B2-C (named type III) and L-A1-B2-C (named type IV), respectively. These splice variants were also demonstrated in placenta. PSG4 cDNA had a type IIa (L-N-A1-B2-C) and PSG7 cDNA a type I (L-N-A1-A2-B2-C) domain arrangement. PSG1, PSG4, PSG5 were found at highest frequency while PSG8 and PSG12 cDNA clones were not detected.