title: MICAL-1 isoforms, novel rab1 interacting proteins.
abstract: Rab1 GTPases participate in regulating the vesicular transport of ER-Golgi compartments. Recently, GM130, p115, and Golgin-84 were identified as effectors of the active conformation of rab1. Here, we describe a novel protein, MICAL-1b, a splice variant of the MICAL-1a protein. Using the yeast two-hybrid system, we showed that it specifically interacts with rab1 in a nucleotide-dependent manner. The interaction was confirmed by GST pulldown experiments. Cell fractionation revealed that in contrast to the mainly membrane-associated rab1 effector GM130, MICAL-1 displays a predominantly cytosolic localization. We mapped the rab1 interacting domain to the C-terminus of MICAL-1, which also mediates binding to the intermediate filament vimentin. Therefore, the interaction of MICAL-1 and rab1 might provide a link between the Golgi apparatus and the intermediate filament cytoskeleton. We suggest that MICAL-1 isoforms with their multidomain structure are novel rab1 interacting proteins that function as scaffold proteins connecting different components in the cell.
authors.affiliation: Department of Experimental Tumorbiology, University of Muenster, Badestr. 9, D-48149, Muenster, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Weide
authors.forename: Julia
authors.initials: J
authors.lastname: Teuber
authors.forename: Michael
authors.initials: M
authors.lastname: Bayer
authors.forename: Angelika
authors.initials: A
authors.lastname: Barnekow
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001665:Binding Sites; D001693:Biological Transport, Active; D002460:Cell Line; D006224:Cricetinae; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D008840:Microfilament Proteins; D006899:Mixed Function Oxygenases; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D020798:Two-Hybrid System Techniques; D014746:Vimentin / Q000378:metabolism; D020761:rab1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000096985:Calponins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D006160:Guanosine Triphosphate; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D008840:Microfilament Proteins; D006899:Mixed Function Oxygenases; D020033:Protein Isoforms; D014746:Vimentin; D020761:rab1 GTP-Binding Proteins; C455272:MICAL1 protein, human; D000096985:Calponins