Conservation of pregnancy-specific glycoprotein (PSG) N domains following independent expansions of the gene families in rodents and primates

Relative conservation of primate N domains and rodent N1 domains suggests that, despite independent gene family expansions and structural diversification, mouse and human PSGs retain conserved functions. Human PSG gene family expansion and homogenisation suggests that evolution occurred in a concerted manner that maintains similar functions of PSGs, whilst increasing gene dosage of the family as a whole. In the mouse, gene family expansion, coupled with local diversification of the CFG face, suggests selection both for increased gene dosage and diversification of function. Partial conservation of RGD and RGD-like tri-peptides in primate and rodent N and N1 domains, respectively, supports a role for these motifs in PSG function.