Partial characterization of an erythropoiesis inhibitory factor

Abstract An inhibitory factor of erythropoiesis, obtained from normal human urine, is indicated to be a complex of a fragment of α 1 -acid glycoprotein and prostaglandin F 2α . Immunoelectrophoresis reveals two protein components in the EIF complex which separate during acrylamide gel electrophoresis. A γ-globulin (MW 185,000) is a carrier of the complex. A fragment of α 1 -acid glycoprotein (MW 9300) retains the inhibitory factor, PGF 2α . Noncovalent forces bind the PGF 2α to the protein, and PGF 2α can be extracted with benzene.