PSG is an alias for the gene, Pregnancy specific beta-1-glycoprotein 5, in humans. Other names include: Pregnancy-specific beta-1-glycoprotein 5; PSBG-5; Pregnancy-specific glycoprotein 5; Fetal liver non-specific cross-reactive antigen 3; FL-NCA-3; PS-beta-G-5; pregnancy-specific beta 1 glycoprotein. The encoded protein has an amino acid length of 335 and a mass of 37.7 kDa. Other isoforms may exist. PSG is a member of the Immunoglobulin superfamily, CEA family. This gene shares homology with other species, including: Fly.