Selected properties of [ 3H]prostaglandin E 1 binding to dispersed bovine luteal cells

Abstract

Selected properties of [ 3H]prostaglandin (PG) e 1 binding to collagenase dispersed bovine luteal cells were studied and compared with those observed in luteal plasma membranes. [ 3H]-PGE 1 specific binding to a relatively homogeneous population of luteal cells was a rapid ( K 1 = 4.2 × 10 5 M −1 · sec −1), reversible ( K −1 = 3.9 × 10 −3 sec −2), saturable and specific process at 38°C. The binding was homogeneous with an apparent dissociation constant of 2.4 nM and 1.8 × 10 5 receptors per cell. The presence of increasing amounts of unlabeled PGs inhibited [ 3H]PGE 1 binding in a dose-dependent manner. The potency order for this inhibition of binding was: PGE 2 > PGE 1, (15S)-15-methyl-PGE 2 methyl ester > PGF 2α > PGF 1α > other PGs, PGE, PGF metabolites and PGF analogs. Other than the homogeneous nature of [ 3H]PGE 1 binding and the greater effectiveness of PGE 2 compared to PGE 1 in cells, the rest of the properties of [ 3H]PGE 1 binding to cells were in excellent agreement with those observed in plasma membranes.