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Mol Cell Biol

Title:		Agonist-specific conformational changes in the yeast alpha-factor pheromone receptor
Author(s):		Bukusoglu G; Jenness DD;
Address:		"Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, 01655-0122, USA"
Journal Title:		Mol Cell Biol
Year:		1996
Volume:		16
Issue:		9
Page Number:		4818 - 4823
DOI:		10.1128/MCB.16.9.4818
ISSN/ISBN:		0270-7306 (Print) 1098-5549 (Electronic) 0270-7306 (Linking)
Abstract:		"The yeast alpha-factor pheromone receptor is a member of the G-protein-coupled receptor family. Limited trypsin digestion of yeast membranes was used to investigate ligand-induced conformational changes in this receptor. The agonist, alpha-factor, accelerated cleavage in the third intracellular loop, whereas the antagonist, desTrp1,Ala3-alpha-factor, reduced the cleavage rate. Thus, the enhanced accessibility of the third intracellular loop is specific to the agonist. alpha-Factor inhibited cleavage weakly at a second site near the cytoplasmic terminus of the seventh transmembrane helix, whereas the antagonist showed a stronger inhibition of cleavage at this site and at another site in the C-terminal domain of the receptor. The alpha-factor-induced conformational changes appeared to be inherent properties of the receptor, as they were retained in G-protein-deficient mutants. Moreover, a mutant receptor (ste2-L236H) that affects the third loop and is defective for G-protein coupling retained the ability to undergo the agonist-induced conformational changes. These results are consistent with a model in which G-protein activation is limited by the availability of specific contacts between the G protein and the third intracellular loop of the receptor. The antagonist appears to promote a distinct conformational state that differs from either the unoccupied or the agonist-occupied state"
Keywords:		"Amino Acid Sequence Fungal Proteins/agonists/*chemistry/physiology GTP-Binding Proteins/metabolism Ligands Mating Factor Molecular Sequence Data Peptides/physiology Protein Binding *Protein Conformation Receptors, Mating Factor Receptors, Peptide/agonists;"
Notes:		"MedlineBukusoglu, G Jenness, D D eng GM34719/GM/NIGMS NIH HHS/ Research Support, U.S. Gov't, P.H.S. 1996/09/01 Mol Cell Biol. 1996 Sep; 16(9):4818-23. doi: 10.1128/MCB.16.9.4818"