Characterization of the human GARP (Golgi associated retrograde protein) complex.
The Golgi associated retrograde protein complex (GARP) or Vps fifty-three (VFT) complex is part of cellular inter-compartmental transport systems. Here we report the identification of the VFT tethering factor complex and its interactions in mammalian cells. Subcellular fractionation shows that human Vps proteins are found in the smooth membrane/Golgi fraction but not in the cytosol. Immunostaining of human Vps proteins displays a vesicular distribution most concentrated at the perinuclear envelope. Co-staining experiments with endosomal markers imply an endosomal origin of these vesicles. Significant accumulation of VFT complex positive endosomes is found in the vicinity of the Trans Golgi Network area. This is in accordance with a putative role in Golgi associated transport processes. In Saccharomyces cerevisiae, GARP is the main effector of the small GTPase Ypt6p and interacts with the SNARE Tlg1p to facilitate membrane fusion. Accordingly, the human homologue of Ypt6p, Rab6, specifically binds hVps52. In human cells, the "orphan" SNARE Syntaxin 10 is the genuine binding partner of GARP mediated by hVps52. This reveals a previously unknown function of human Syntaxin 10 in membrane docking and fusion events at the Golgi. Taken together, GARP shows significant conservation between various species but diversification and specialization result in important differences in human cells.
Liewen
Heike
H
Medical Department I, University of the Saarland, Homburg 66421, Germany.
Meinhold-Heerlein
Ivo
I
Oliveira
Vasco
V
Schwarzenbacher
Robert
R
Luo
Guorong
G
Wadle
Andreas
A
Jung
Martin
M
Pfreundschuh
Michael
M
Stenner-Liewen
Frank
F
D000818:Animals; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004285:Dogs; D015870:Gene Expression / Q000235:genetics; D006056:Golgi Apparatus / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008285:Major Histocompatibility Complex / Q000235:genetics / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D021381:Protein Transport; D011506:Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D050765:Qa-SNARE Proteins; D017422:Sequence Analysis, DNA; D014162:Transfection; D022161:Transport Vesicles / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020691:rab GTP-Binding Proteins / Q000378:metabolism
D018076:DNA, Complementary; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D011506:Proteins; D050765:Qa-SNARE Proteins; C094135:Rab6 protein; C115740:VPS52 protein, human; C503307:VPS53 protein, human; C486749:VPS54 protein, human; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins