title: High-affinity prostaglandin E receptors attenuate adenylyl cyclase activity in isolated bovine myometrial membrane.
abstract: Purified bovine myometrial plasma membranes were used to characterize prostaglandin (PG) E2 binding. Two binding sites were found: a high-affinity site with a dissociation constant (KD) of 0.27 +/- 0.08 nM and maximum binding (Bmax) of 102.46 +/- 8.6 fmol/mg membrane protein, and a lower affinity site with a KD = 6.13 +/- 0.50 nM and Bmax = 467.93 +/- 51.63 fmol/mg membrane protein. Membrane characterization demonstrated that [3H]PGE2 binding was localized in the plasma membrane. In binding competition experiments, unlabelled PGE1 displaced [3H]PGE2 from its receptor at the same concentrations as did PGE2. Neither PGF2 alpha nor PGD2 effectively competed for [3H]PGE2 binding. Adenylyl cyclase activity was inhibited at concentrations of PGE2 that occupy the high-affinity receptor. These data demonstrate that two receptor sites, or states of binding within a single receptor, are present for PGE2 in purified myometrial membranes. PGE2 inhibition of adenylyl cyclase activity support the view that cAMP has a physiological role in the regulation of myometrial contractility by PGE2.
authors.affiliation: Heritage Cardiovascular Disease Group, University of Alberta, Edmonton, Canada.
authors.forename: R W
authors.initials: RW
authors.lastname: Lerner
authors.forename: G D
authors.initials: GD
authors.lastname: Lopaschuk
authors.forename: P M
authors.initials: PM
authors.lastname: Olley
mesh_terms: D015720:5'-Nucleotidase / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000408:Alamethicin / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D005260:Female; D005966:Glucuronidase / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D009119:Muscle Contraction / Q000187:drug effects; D009215:Myometrium / Q000201:enzymology*; D009245:NADH Dehydrogenase / Q000378:metabolism; D011458:Prostaglandins E / Q000378:metabolism*; D011982:Receptors, Prostaglandin / Q000378:metabolism*; D018078:Receptors, Prostaglandin E; D013347:Subcellular Fractions / Q000201:enzymology / Q000378:metabolism
chemical_list: D011458:Prostaglandins E; D011982:Receptors, Prostaglandin; D018078:Receptors, Prostaglandin E; D000408:Alamethicin; D009245:NADH Dehydrogenase; D015720:5'-Nucleotidase; D005966:Glucuronidase; D000262:Adenylyl Cyclases