title: A conserved GTPase-containing complex is required for intracellular sorting of the general amino-acid permease in yeast.
abstract: The Saccharomyces cerevisiae general amino-acid permease, Gap1p, is a model for membrane proteins that are regulated by intracellular sorting according to physiological cues set by the availability of amino acids. Here, we report the identification of a conserved sorting complex for Gap1p, named the GTPase-containing complex for Gap1p sorting in the endosomes (GSE complex), which is required for proper sorting of Gap1p from the late endosome for eventual delivery to the plasma membrane. The complex contains two small GTPases (Gtr1p and Gtr2p) and three other proteins (Ybr077c, Ykr007w and Ltv1p) that are located in the late endosomal membrane. Importantly, Gtr2p interacts with the carboxy (C)-terminal cytosolic domain of Gap1p and a tyrosine-containing motif in this domain is necessary both to bind Gtr2p and to direct sorting of Gap1p to the plasma membrane. Together, these studies provide evidence that the GSE complex has a key role in trafficking Gap1p out of the endosome and may serve as coat proteins in this process.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
authors.forename: Minggeng
authors.initials: M
authors.lastname: Gao
authors.forename: Chris A
authors.initials: CA
authors.lastname: Kaiser
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D026905:Amino Acid Transport Systems / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D011992:Endosomes / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism / Q000648:ultrastructure; D046911:Macromolecular Substances / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D026905:Amino Acid Transport Systems; C491145:GAP1 protein, S cerevisiae; C121263:GTR2 protein, S cerevisiae; C121262:Gtr1 protein, S cerevisiae; C501335:LTV1 protein, S cerevisiae; D046911:Macromolecular Substances; D029701:Saccharomyces cerevisiae Proteins; D019204:GTP-Binding Proteins; D020559:Monomeric GTP-Binding Proteins