Properties of [ 3H] prostaglandin F 2α binding to dispersed bovine luteal cells

Abstract

Intact viable bovine luteal cell suspensions prepared by collagenase digestion of luteal tissue were used in studying the selected properties of [ 3H] prostaglandin (PG) F 2α binding and compared with those observed in plasma membranes. [ 3H]PGF 2α specific binding to luteal cells was a rapid (K 1 = 8.4 × 10 4M −1 2 α S −1), reversible (K −1 = 1.8 × 10 −4S −1) and saturable process at 24°. There was a single class of receptors with an apparent dissociation constant of 10.6 nM and 1.8 × 10 5 receptors per cell. The presence of increasing amounts of unlabeled PGs inhibited [ 3H]PGF 2α binding in a dose-dependent manner. The potency order for this inhibition was: (15S) 15-methyl-PGF 2α methyl ester > ICI-80,996 > PGF 2α > ICI-81,008 > PGF 1α > PGE 2, (15S) 15-methyl-PGE 2 methyl ester > PGF 2α metabolites > other PGs, PGF 1α metabolites and PGE metabolites. Other than the homegeneous nature of binding and a greater association rate in cells, the rest of the [ 3H]PGF 2α binding properties in cells were in good agreement with those observed in plasma membranes.