title: The N-terminus of the yeast G protein-coupled receptor Ste2p plays critical roles in surface expression, signaling, and negative regulation.
abstract: G protein-coupled receptors (GPCRs) are found in all eukaryotic cells examined to date where they function as membrane-bound proteins that bind a multitude of extracellular ligands to initiate intracellular signal transduction systems controlling cellular physiology. GPCRs have seven heptahelical membrane spanning domains connected by extracellular and intracellular loops with an extracellular N-terminus and an intracellular C-terminus. The N-terminus has been the least studied domain of most GPCRs. The yeast Ste2p protein, the receptor for the thirteen amino acid peptide pheromone α-factor, has been used extensively as a model to study GPCR structure and function. In this study we constructed a number of deletions of the Ste2p N-terminus and uncovered an unexpected function as a negative regulatory domain. We examined the role of the N-terminus in expression, signaling function and ligand-binding properties and found that the residues 11-30 play a critical role in receptor expression on the cell surface. The studies also indicated that residues 2-10 of the N-terminus are involved in negative regulation of signaling as shown by the observation that deletion of these residues enhanced mating and gene induction. Furthermore, our results indicated that the residues 21-30 are essential for optimal signaling. Overall, we propose that the N-terminus of Ste2p plays multiple regulatory roles in controlling receptor function.
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States.
authors.forename: M Seraj
authors.initials: MS
authors.lastname: Uddin
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States.
authors.forename: Melinda
authors.initials: M
authors.lastname: Hauser
authors.affiliation: Department of Chemistry, and Macromolecular Assemblies Institute, College of Staten Island, CUNY, New York, NY 10314, United States; Graduate School and University Center, CUNY, New York, NY 10314, United States.
authors.forename: Fred
authors.initials: F
authors.lastname: Naider
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States. Electronic address: jbecker@utk.edu.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Becker
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D015966:Gene Expression Regulation, Fungal; D008024:Ligands; D000072235:Mating Factor; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism; D051964:Receptors, Mating Factor / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction; D013499:Surface Properties
chemical_list: D008024:Ligands; D010455:Peptides; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; C498031:STE2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor
keywords: G protein-coupled receptor (GPCR); Saccharomyces cerevisiae; Signal transduction; Ste2p; Yeast