Identification and characterization of prostaglandin-binding components in rat ileum

A specific prostaglandin E2 (PGE2) binding component was identified in the membrane fractions of rat ileum. Two ligands, 3H-PGE2 and 14C-PGE2, competed for the binding sites in crude homogenates of ileum during competition experiments, demonstrating the presence of a limited number of binding sites. There was enhancement in the specific 3H-PGE2 binding to particulate fractions over control when endogenous prostaglandin synthesis was blocked by the administration of indomethacin to rats prior to sacrifice. The specific prostaglandin-binding protein was purified by a combination of [NH4]2SO4 fractionation and Sephacryl S-200 column chromatographic techniques, and shown to be active after these biochemical steps.