Characterization of a mammalian Golgi-localized protein complex, COG, that is required for normal Golgi morphology and function.
Multiprotein complexes are key determinants of Golgi apparatus structure and its capacity for intracellular transport and glycoprotein modification. Three complexes that have previously been partially characterized include (a) the Golgi transport complex (GTC), identified in an in vitro membrane transport assay, (b) the ldlCp complex, identified in analyses of CHO cell mutants with defects in Golgi-associated glycosylation reactions, and (c) the mammalian Sec34 complex, identified by homology to yeast Sec34p, implicated in vesicular transport. We show that these three complexes are identical and rename them the conserved oligomeric Golgi (COG) complex. The COG complex comprises four previously characterized proteins (Cog1/ldlBp, Cog2/ldlCp, Cog3/Sec34, and Cog5/GTC-90), three homologues of yeast Sec34/35 complex subunits (Cog4, -6, and -8), and a previously unidentified Golgi-associated protein (Cog7). EM of ldlB and ldlC mutants established that COG is required for normal Golgi morphology. "Deep etch" EM of purified COG revealed an approximately 37-nm-long structure comprised of two similarly sized globular domains connected by smaller extensions. Consideration of biochemical and genetic data for mammalian COG and its yeast homologue suggests a model for the subunit distribution within this complex, which plays critical roles in Golgi structure and function.
Ungar
Daniel
D
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Oka
Toshihiko
T
Brittle
Elizabeth E
EE
Vasile
Eliza
E
Lupashin
Vladimir V
VV
Chatterton
Jon E
JE
Heuser
John E
JE
Krieger
Monty
M
Waters
M Gerard
MG
D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D003001:Cloning, Molecular; D017124:Conserved Sequence; D006056:Golgi Apparatus / Q000502:physiology*; D006801:Humans; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000502:physiology; D046912:Multiprotein Complexes; D009154:Mutation; D011487:Protein Conformation; D021122:Protein Subunits; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D051381:Rats; D029701:Saccharomyces cerevisiae Proteins
D033942:Adaptor Proteins, Vesicular Transport; C486489:COG1 protein, human; C401396:COG3 protein, S cerevisiae; C498528:COG3 protein, human; D002352:Carrier Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D021122:Protein Subunits; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; C090202:COG2 protein, human