Multiple G proteins compete for binding with the human gonadotropin releasing hormone receptor.
The GnRH receptor is coupled to G proteins of the families G(q) and G(11). G(q) and G(11) coupling leads to intracellular signaling through the phospholipase C pathway. GnRHR coupling to other G proteins is controversial. This study provides evidence that G protein families G(s), G(i), G(q) and G(11) complete for binding with the GnRHR. We quantified interactions of over-expressed G proteins with GnRHR by a competitive binding approach, using measurements of second messengers, IP and cAMP. Transient co-transfection of HEK293 cells with human WT GnRHR and with stimulatory and inhibitory G proteins (G(q), G(11) and G(s), G(i)) led to either production or inhibition of total inositol phosphate (IP) production, depending on the G protein that was over-expressed. Studies were conducted in different human (COS7, HeLa) and rodent-derived (CHO-K1, GH(3)) cell lines in order to confirm that G protein promiscuity observed with the GnRHR was not limited to a particular cell type.
Knollman
Paul E
PE
Divisions of Neuroscience and Reproductive Biology, ONPRC/OHSU, Oregon National Primate Research Center, 505 NW 185th Avenue, Beaverton, Oregon 97006, USA.
Conn
P Michael
PM
D000818:Animals; D001667:Binding, Competitive; D003994:Bucladesine / Q000494:pharmacology; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D037342:Pertussis Toxin / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D011966:Receptors, LHRH / Q000378:metabolism*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D004963:Estrenes; D011760:Pyrrolidinones; D011966:Receptors, LHRH; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D005576:Colforsin; D003994:Bucladesine; D002772:Cholera Toxin; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins