title: Negative regulatory activity of a prostaglandin F2 alpha receptor associated protein (FPRP).
abstract: The cDNA has been cloned for a protein which copurifies with and colocalizes with [3H]PGF2 alpha binding activity. This cloning was based on prior purification of the [3H]PGF2 alpha binding complex from pregnant corpus luteum, antibody production against the protein of interest, and antibody screening of a rat ovary cDNA expression library. Here I report on the activity of this prostaglandin F2 alpha receptor (FP) associated protein (FPRP). Expression of the FPRP cDNA in COS cells results in production of a full length (approximately 130 kD) immunoreactive molecule with an endoplasmic reticulum and Golgi network distribution similar to that seen in granulosa lutein cells. COS cell expressed FPRP inhibits binding of [3H]PGF2 alpha to FP of COS cell origin or FP expressed from cotransfected rat or mouse FP cDNA in a dose-dependent manner. This inhibition of [3H]PGF2 alpha binding by FPRP occurs only when the FPRP cDNA is expressed in the same cell as the FP resides, reaches a maximum of approximately 80%, and is unaffected by second messenger perturbing agents such as phorbol ester, 8-Br-cAMP, calcium ionophore A23187, and okadaic acid. Scatchard analysis indicates that FPRP induces a decrease in receptor number rather than affinity constant, suggesting a non-competitive means of inhibition. Molecular dissection of the FPRP protein indicates that two portions of the molecule play a role in the inhibition of FP. Whether FPRP is an FP-associated regulatory molecule, an FP subunit, or a receptor for a PGF2 alpha-antagonistic ligand is presently unknown. Physiological relevance and significance of FPRP are discussed. During the course of these experiments it was necessary to clone the rat FP cDNA.
authors.affiliation: Department of Pathology, University of Colorado Health Sciences Center, Denver 80262, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Orlicky
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D019556:COS Cells; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D015237:Dinoprost / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D019319:Okadaic Acid / Q000494:pharmacology; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011982:Receptors, Prostaglandin / Q000235:genetics / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection
chemical_list: D018076:DNA, Complementary; D009363:Neoplasm Proteins; D011506:Proteins; C104480:Ptgfrn protein, rat; D011982:Receptors, Prostaglandin; D019319:Okadaic Acid; D015124:8-Bromo Cyclic Adenosine Monophosphate; D015237:Dinoprost; D013755:Tetradecanoylphorbol Acetate