Domains within the GARP subunit Vps54 confer separate functions in complex assembly and early endosome recognition.
Tethering complexes contribute to the specificity of membrane fusion by recognizing organelle features on both donor and acceptor membranes. The Golgi-associated retrograde protein (GARP) complex is required for retrograde traffic from both early and late endosomes to the trans-Golgi network (TGN), presenting a paradox as to how a single complex can interact specifically with vesicles from multiple upstream compartments. We have found that a subunit of the GARP complex, Vps54, can be separated into N- and C-terminal regions that have different functions. Whereas the N-terminus of Vps54 is important for GARP complex assembly and stability, a conserved C-terminal domain mediates localization to an early endocytic compartment. Mutation of this C-terminal domain has no effect on retrograde transport from late endosomes. However, a specific defect in retrieval of Snc1 from early endosomes is observed when recycling from late endosomes to the Golgi is blocked. These data suggest that separate domains recruit tethering complexes to different upstream compartments to regulate individual trafficking pathways.
Quenneville
Nicole R
NR
Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Departments of Medical Genetics and Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada.
Chao
Tzu-Yuan
TY
McCaffery
J Michael
JM
Conibear
Elizabeth
E
D000595:Amino Acid Sequence; D004705:Endocytosis; D011992:Endosomes / Q000737:chemistry / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D008969:Molecular Sequence Data; D017354:Point Mutation; D017434:Protein Structure, Tertiary / Q000235:genetics; D050683:R-SNARE Proteins / Q000378:metabolism; D051964:Receptors, Mating Factor / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
D050683:R-SNARE Proteins; D051964:Receptors, Mating Factor; C083241:SNC1 protein, S cerevisiae; C081863:STE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C117606:VPS54 protein, S cerevisiae; D033921:Vesicular Transport Proteins