---------------------------------------------------------------------------- GPCR mutations that cause agonism-antagonism switching or alter efficacies cell parameters (expression level of G proteins, etc.) also control agonism Kinzer-Ursem and Linderman, PloS Comput Biol 2007 3(1):e6 ---------------------------------------------------------------------------- beta2AR III:7 D->E decreases agonist and antagonist affinities; some antagonists become partial agonists (alprenolol and pindolol, but not isoproterenol). D->N decreases agonist and antagonist affinities, no switching occurs. Strader et al. JBC 264(28):16470 (1989) betaAR several antagonists at B1AR's and B2AR's are agonists at B3AR's Gros et al. Eur J Biochem 251:590 (1998) betaAR avian *in membranes but not purified/reconstituted* Cterm truncations result in constitutive activity, conversion of antagonists to agonists, and increased efficacy of partial agonists Parker and Ross JBC 266(15):9987 (1991) B2R human bradykinin receptor mutation of T/S cluster in tail decreases desensitization, increases receptor number and basal activity (BK aff ~wt) PI hydrolysis rate, -/+ BK action of NPC17731, HOE140 wt 0.03 / 0.86 agonists tail mut 0.19 / 1.50 inverse agonists postulate R <-> Rintermed <-> R* with Rintermed stab by partial ag/antags and R* stab by full agonists Fathy et al. JBC 274(42):29603 (1999) bradykinin B2R human constitutively activating mutations N113A (III:10) and W256F (VI:16) convert inverse agonists HOE140 (peptidic) and LF160335 (nonpeptidic) into agonists Marie et al. Mol Pharm 55:92 (1999) CB1 cannabinoid R human F200A (III:11) incr constit act (Gi) and converts AM2233 from agonist to inverse agonist; effects of certain other agonists/antagonists unchanged Shen et al. Eur J Pharmacol Jan 23, 2006 [epub] CCKB/gastrin R human - several point mutations modulate the efficacy of benzodiazepine-type antagonists, while maintaining normal CCK8 agonism: L365,260 weak partial agonist (%10) V:3 S->A incr efficacy VI:19 V->A " VI:23 N->L " VII:10 S->A " YM022 antagonist VI:16 W->A incr efficacy -> partial agonist L740,093S partial agonist (%30) V:3 S->A incr efficacy VI:19 V->A " VII:10 S->A " II:25 T->A decr efficacy VI:16 W->A " VI:20 Y->A " (-> full antagonist) VI:23 N->L " Blaker et al. Mol Pharm 54:857 (1998) CCKB/gastrin R species differences modulate efficacies of partial agonists but not their affinities or affinity/efficacy of CCK8 VI:10 human V340 mouse L increased efficacy VI:14 human L344 mouse V increased efficacy VI:19 human V349 dog L increased efficacy Kopin et al. PNAS USA 94:11043 (1997) CCKBR human mutants well-expressed, Emax ~wt for CCK4,CCK8 affinity: x=IC50 incr >5x | Emax if sig diff from wt receptor CCK4,CCK8 PD135158,PD136450| PD135158 PD136450 L740-093S (peptides) (peptoids) | (20% at wt) (42%) (30%; nonpept) I:7 Y61A x | 16 12 II:25 T111A x | 16 6 IV:18 M186A x x | 41 (incr) 67 (incr) 9 V:11 F227A | 0 8 VI:16 W346A | 43 (incr) 12 VI:19 V349A x | 3 3 72 (incr) VI:20 Y350A | 0 0 0 VI:23 N353L x | 15 12 VI:24 T354A x | 5 Blaker et al. Mol Pharm 58:399 (2000) D1R human VI:17 L286A (but not Y) constitutively active, and antagonist SCH23390 becomes a partial agonist Cho et al. Mol Pharm 50:1338 (1996) D2R human short splice variant VI:2 T343R not constit active but increases efficacy of most partial agonists Pauwels et al. Biochem Pharmacol 62:723 (2001) * note another group found this mutant IS constit active GABAB1R rat coexpressed with GABAB2R; Y366A in lobe II of the NTD makes the agonist baclofen into an antagonist Galvez et al. JBC 275(52):41166 (2000) GnRHR human V197A/W205H in EC2 convert an antagonist to an agonist Ott et al. Mol Endocrinol 16(5):1079 (2002) MC1R human II:8 C78G agonist NDP-MSH (but not alpha-MSH) -> antagonist Frandberg et al. BBRC 281:851 (2001) m5R VI:12 F->P converts some antagonists to agonists (constitutively active V,T>L>C,A,N not Q,G,W,P) Spalding et al. JBC 273(34):21563 (1998) nociceptinR (ORL1R) human III:8 Y131A lofentanil agonist -> antagonist VI:16 W276A lofentanil,HP5 agonists -> partial agonists Mouledous et al. Mol Pharm 57:495 (2000) oxytocinR; arginine vasopressin (AVP) is partial agonist in some systems, becomes full agonist with these mutations to the corresp residues in VP1aR although affinity stays about the same V:11 Y -> F (225 in VP1aR) VI:12 F -> Y (300 in VP1aR) Hibert et al. J Receptor Sig Trans Res 19:589 (1999) opioid receptors IV:15 S->L many alkaloid and peptide antagonists (some exceptions) become agonists in the mu, delta, and mu/delta chimeric receptors; relative affinities maintained. S->T does not have this effect, at least in mu. Claude et al. PNAS USA 93:5715 (1996) delta opioidR mouse III:7 D128K decreases expression, decreases DPDPE and naloxone affinity, makes naloxone an agonist; D128A maintains expression, affinities and ag/antag properties; D128H decreases expression (affinities not done); all three mutants are constitutively active; D128R not expressed Cavalli et al. Neuroscience 93:1025 (1999) mu opioidR rat VI:20 H297N,Q antag naloxone -> partial agonist, partial agonist buprenorphine -> increased efficacy; in contrast, no change of efficacy of peptide ligands; suggest effect is indirect rather than due to direct contact H297A,L,F,D,E,K,R expr but insufficient radioligand binding for characterization Spivak et al. Mol Pharm 52:983 (1997) secretinR double mutant II:7 H->R and VI:5 T->P constitutively active; the natural agonist secretin becomes an inverse agonist. II:7 H->R alone is very weakly constitutively active and VI:5 T->P is weakly constitutively active; agonist secretin can produce further activation. In the PTHR, each of these mutations is constitutively activating, and was found in Jansen's metaphyseal chondroplasia. Ganguli et al. JPET 286:593 (1998). STE2 S. cerevisiae desTrp1[Ala3,Nle12]alpha-factor (antagonist at wt)-> agonist at S219P (V) and S259P (VI) receptors, but Kd >100microM Abel et al. Biochim Biophys Acta 1448:12 (1998) ----------------------------------------------------------------------------