title: Adaptor protein Ruk/CIN85 is associated with a subset of COPI-coated membranes of the Golgi complex.
abstract: Regulator of ubiquitous kinase/Cbl-interacting protein of 85 kDa (Ruk/CIN85) and CD2-associated protein/Cas ligand with multiple SH3 domains (CD2AP/CMS) comprise a family of vertebrate adaptor proteins involved in several important cellular processes, including downregulation of activated receptor tyrosine kinases, regulation of cytoskeletal rearrangements, phosphatidylinositol 3-kinase (PI 3-kinase) signalling and apoptosis. The role of Ruk/CIN85 as a scaffold protein involved in membrane trafficking processes has been demonstrated in model cell systems. However, intracellular localization of endogenous Ruk/CIN85 has never been comprehensively assessed. We carried out detailed studies of subcellular distribution of Ruk/CIN85 in adherent cultured human cells using antibodies that recognize distinct epitopes of the protein and revealed a punctate immunostaining pattern, common for proteins involved in intracellular trafficking processes. Our data indicate that Ruk/CIN85 is distributed between several different membrane trafficking compartments, but the major pool of Ruk/CIN85 is associated with the Golgi complex, mainly with a subpopulation of COPI-coated vesicles involved in retrograde endoplasmic reticulum-Golgi and intra-Golgi transport. This localization pattern is dependent on the integrity of Golgi complex and intact microtubular network. Only a small pool of Ruk/CIN85 is present in compartments involved in clathrin-mediated endocytosis and sorting. These results suggest that endogenous Ruk/CIN85 may be involved in regulation of specific membrane trafficking processes.
authors.affiliation: School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3US, Wales, UK.
authors.forename: Serhiy
authors.initials: S
authors.lastname: Havrylov
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Ichioka
authors.forename: Kate
authors.initials: K
authors.lastname: Powell
authors.forename: Emma B
authors.initials: EB
authors.lastname: Borthwick
authors.forename: Jolanta
authors.initials: J
authors.lastname: Baranska
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Maki
authors.forename: Vladimir L
authors.initials: VL
authors.lastname: Buchman
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D020126:Brefeldin A / Q000378:metabolism; D022181:COP-Coated Vesicles / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism; D020755:Coat Protein Complex I / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology; D011992:Endosomes / Q000378:metabolism; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015415:Biomarkers; D002966:Clathrin; D020755:Coat Protein Complex I; D011500:Protein Synthesis Inhibitors; D011993:Recombinant Fusion Proteins; C433810:SH3KBP1 protein, human; D020126:Brefeldin A; D066246:ErbB Receptors; D020823:ADP-Ribosylation Factor 1