title: Clathrin facilitates the internalization of seven transmembrane segment receptors for mating pheromones in yeast.
abstract: The role of clathrin in endocytosis of the yeast phermone receptors was examined using strains expressing a temperature-sensitive clathrin heavy chain. The yeast phermone receptors belong to the family of seven transmembrane segment, G-protein-coupled receptors. A rapid and reversible defect in uptake of radiolabeled alpha-factor pheromone occurred when the cells were transferred to the nonpermissive temperature. Constitutive, pheromone-independent internalization of newly synthesized a-factor phermone receptor was also rapidly inhibited in mutant strains at the nonpermissive temperature. In both cases residual endocytosis, 30-50% of wild-type levels, was detected in the absence of functional clathrin heavy chain. Once internalized, the a-factor receptor was delivered to the vacuole at comparable rates in chc1-ts and wild-type cells at the nonpermissive temperature. Clathrin heavy chain was also required for maximal uptake of a mutant a-factor receptor which is dependent on pheromone for internalization. In the presence of a-factor, the internalization rate of the mutant receptor in chc1-ts cells at the nonpermissive temperature was 2.5 times slower than the rate observed for endocytosis of the mutant receptor in wild-type cells. These experiments provide in vivo evidence that clathrin plays an important role in the endocytosis of the seven trans-membrane segment pheromone receptors in yeast.
authors.affiliation: Department of Biological Chemistry, University of California at Los Angeles School of Medicine 90024.
authors.forename: P K
authors.initials: PK
authors.lastname: Tan
authors.forename: N G
authors.initials: NG
authors.lastname: Davis
authors.forename: G F
authors.initials: GF
authors.lastname: Sprague
authors.forename: G S
authors.initials: GS
authors.lastname: Payne
mesh_terms: D001692:Biological Transport; D002966:Clathrin / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D019204:GTP-Binding Proteins / Q000378:metabolism; D005800:Genes, Fungal; D005838:Genotype; D007700:Kinetics; D000072235:Mating Factor; D010455:Peptides / Q000378:metabolism*; D010675:Pheromones / Q000378:metabolism*; D011402:Pronase; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D014157:Transcription Factors; D014617:Vacuoles / Q000378:metabolism
chemical_list: D002966:Clathrin; D010455:Peptides; D010675:Pheromones; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide; D014157:Transcription Factors; D000072235:Mating Factor; D011402:Pronase; D019204:GTP-Binding Proteins