Isolation of a pregnancy-associated globulin (PAG) from the rat and preparation of a specific antiserum (anti-PAG).

Isolation of a glycoprotein from serum of pregnant rats has been accomplished by ammonium sulphate precipitation, gel filtration, ion exchange and affinity chromatography. Low concentrations of the protein were detectable in the serum of some of the male rats tested, while somewhat higher concentrations were detected also in the serum of non-pregnant female rats. No relationship could be established between this protein and the well known pregnancy-specific proteins or the alpha 2-acute phase-macroglobulin of the rat, whereas evidence was obtained for a strong cross-reaction with a serum protein of pregnant mice.