title: Differential localization of coatomer complex isoforms within the Golgi apparatus.
abstract: Coatomer, the coat protein of coat protein complex (COP)I-vesicles, is a soluble protein complex made up of seven subunits, alpha-, beta-, beta'-, gamma-, delta-, epsilon-, and zeta-COP. Higher eukaryotes have two paralogous versions of the gamma- and zeta- subunits, termed gamma1- and gamma2-COP and zeta1- and zeta2-COP. Different combinations of these subunits are known to exist within coatomer complexes, and gamma1/zeta1-, gamma1/zeta2-, and gamma2/zeta1-COP represent the major coatomer populations in mammals. The role of COPI vesicles in the early secretory pathway is the subject of considerable debate. To help to resolve this discussion, we used quantitative immunoelectron microscopy and found that significant localization differences for COPI-isoforms do exist, with a preference for gamma1zeta1- and gamma1zeta2-coatomer in the early Golgi apparatus and gamma2zeta1-coatomer in the late Golgi apparatus. These differences suggest distinct functions for coatomer isoforms in a manner similar to clathrin/adaptor vesicles, where different adaptor proteins serve particular transport routes.
authors.affiliation: Biochemistry Center and Department of Neurobiology, University of Heidelberg, 69120 Heidelberg, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Moelleken
authors.forename: Jörg
authors.initials: J
authors.lastname: Malsam
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Betts
authors.forename: Ali
authors.initials: A
authors.lastname: Movafeghi
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Reckmann
authors.forename: Ingrid
authors.initials: I
authors.lastname: Meissner
authors.forename: Andrea
authors.initials: A
authors.lastname: Hellwig
authors.forename: Robert B
authors.initials: RB
authors.lastname: Russell
authors.forename: Thomas
authors.initials: T
authors.lastname: Söllner
authors.forename: Britta
authors.initials: B
authors.lastname: Brügger
authors.forename: Felix T
authors.initials: FT
authors.lastname: Wieland
mesh_terms: D000818:Animals; D001692:Biological Transport; D022181:COP-Coated Vesicles / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D020756:Coatomer Protein / Q000096:biosynthesis / Q000737:chemistry*; D003600:Cytosol / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D007150:Immunohistochemistry; D007668:Kidney / Q000166:cytology; D051379:Mice; D016253:Microscopy, Immunoelectron; D041681:NIH 3T3 Cells; D020033:Protein Isoforms; D051381:Rats
chemical_list: D020756:Coatomer Protein; D020033:Protein Isoforms