Steroid and G Protein Binding Characteristics of the Seatrout and Human Progestin Membrane Receptor α Subtypes and Their Evolutionary Origins

• DOI: 10.1210/en.2006-0974
• Publication Date: 2006-11-03T03:17:59Z
• Authors: Peter Thomas; Y. Pang; J. Dong; P. Groenen; J. Kelder; J. de Vlieg; Y. Zhu; C. Tubbs
• Keywords: 0301 basic medicine; 0303 health sciences; DNA, Complementary; Bioinformatics; Cell Membrane; DNA Mutational Analysis; Flow Cytometry; Binding, Competitive; Immunohistochemistry; Second Messenger Systems; Recombinant Proteins; Cell Line; Receptors, G-Protein-Coupled; Evolution, Molecular; 03 medical and health sciences; GTP-Binding Proteins; Mutation; Animals; Humans; Immunoprecipitation; Protein Isoforms; Progestins; Receptors, Progesterone; Phylogeny

A novel progestin receptor (mPR) with seven-transmembrane domains was recently discovered in spotted seatrout and homologous genes were identified other vertebrates. We show that cDNAs for the mPR alpha subtypes from (st-mPRalpha) humans (hu-mPRalpha) encode receptors display many functional characteristics of G protein-coupled receptors. Flow cytometry immunocytochemical staining whole MDA-MB-231 cells stably transfected mPRalphas using antibodies directed against their N-terminal regions are localized on plasma membrane suggest domain is extracellular. Both recombinant st-mPRalpha hu-mPRalpha high affinity (Kd 4.2-7.8 nm), limited capacity (Bmax 0.03-0.32 displaceable binding specific progestins. Progestins activate a pertussis toxin-sensitive inhibitory protein (G(i)) to down-regulate membrane-bound adenylyl cyclase activity both st-mPRalpha- hu-mPRalpha-transfected cells. Coimmunoprecipitation experiments demonstrate directly coupled G(i) protein. Similar receptors, dissociation receptor/G complex results decrease ligand mutation C-terminal, third intracellular loop causes loss ligand-dependent activation. Phylogenetic analysis indicates mPRs members progesterone adipoQ (PAQR) subfamily only present chordates, whereas PAQRs also occur invertebrates plants. Progesterone related hemolysin3 family have origins Eubacteria. Thus, arose Eubacteria independently GPCR superfamily, which Archeabacteria, suggesting convergent evolution hormone proteins.