| Title: | A limited spectrum of mutations causes constitutive activation of the yeast alpha-factor receptor |
| Author(s): | Sommers CM; Martin NP; Akal-Strader A; Becker JM; Naider F; Dumont ME; |
| Address: | "Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA" |
| ISSN/ISBN: | 0006-2960 (Print) 0006-2960 (Linking) |
| Abstract: | "Activation of G protein coupled receptors (GPCRs) by binding of ligand is the initial event in diverse cellular signaling pathways. To examine the frequency and diversity of mutations that cause constitutive activation of one particular GPCR, the yeast alpha-factor receptor, we screened libraries of random mutations for constitutive alleles. In initial screens for mutant receptor alleles that exhibit signaling in the absence of added ligand, 14 different point mutations were isolated. All of these 14 mutants could be further activated by alpha-factor. Ten of the mutants also acquired the ability to signal in response to binding of desTrp(1) inverted question markAla(3)alpha-factor, a peptide that acts as an antagonist toward normal alpha-factor receptors. Of these 10 mutants, at least eight alleles residing in the third, fifth, sixth, and seventh transmembrane segments exhibit bona fide constitutive signaling. The remaining alleles are hypersensitive to alpha-factor rather than constitutive. They can be activated by low concentrations of endogenous alpha-factor present in MATa cells. The strongest constitutively active receptor alleles were recovered multiple times from the mutational libraries, and extensive mutagenesis of certain regions of the alpha-factor receptor did not lead to recovery of any additional constitutive alleles. Thus, only a limited number of mutations is capable of causing constitutive activation of this receptor. Constitutive and hypersensitive signaling by the mutant receptors is partially suppressed by coexpression of normal receptors, consistent with preferential association of the G protein with unactivated receptors" |
| Keywords: | "Amino Acid Sequence Fungal Proteins/genetics GTP-Binding Proteins/metabolism Gene Library Genes, Reporter Lac Operon Mating Factor Membrane Proteins/genetics/metabolism Molecular Sequence Data Mutagenesis Peptides/*metabolism/pharmacology Plasmids Point M;" |
| Notes: | "MedlineSommers, C M Martin, N P Akal-Strader, A Becker, J M Naider, F Dumont, M E eng GM22086/GM/NIGMS NIH HHS/ GM22087/GM/NIGMS NIH HHS/ GM59357/GM/NIGMS NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 2000/06/08 Biochemistry. 2000 Jun 13; 39(23):6898-909. doi: 10.1021/bi992616a" |
