title: Huntingtin-interacting protein 1 (Hip1) and Hip1-related protein (Hip1R) bind the conserved sequence of clathrin light chains and thereby influence clathrin assembly in vitro and actin distribution in vivo.
abstract: Clathrin heavy and light chains form triskelia, which assemble into polyhedral coats of membrane vesicles that mediate transport for endocytosis and organelle biogenesis. Light chain subunits regulate clathrin assembly in vitro by suppressing spontaneous self-assembly of the heavy chains. The residues that play this regulatory role are at the N terminus of a conserved 22-amino acid sequence that is shared by all vertebrate light chains. Here we show that these regulatory residues and others in the conserved sequence mediate light chain interaction with Hip1 and Hip1R. These related proteins were previously found to be enriched in clathrin-coated vesicles and to promote clathrin assembly in vitro. We demonstrate Hip1R binding preference for light chains associated with clathrin heavy chain and show that Hip1R stimulation of clathrin assembly in vitro is blocked by mutations in the conserved sequence of light chains that abolish interaction with Hip1 and Hip1R. In vivo overexpression of a fragment of clathrin light chain comprising the Hip1R-binding region affected cellular actin distribution. Together these results suggest that the roles of Hip1 and Hip1R in affecting clathrin assembly and actin distribution are mediated by their interaction with the conserved sequence of clathrin light chains.
authors.affiliation: G. W. Hooper Foundation, Department of Biopharmaceutical Sciences, University of California, San Francisco, CA 94143-0552, USA.
authors.forename: Chih-Ying
authors.initials: CY
authors.lastname: Chen
authors.forename: Frances M
authors.initials: FM
authors.lastname: Brodsky
mesh_terms: D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D033922:Clathrin Heavy Chains / Q000378:metabolism; D033941:Clathrin Light Chains / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D051379:Mice; D008840:Microfilament Proteins; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D013379:Substrate Specificity; D020798:Two-Hybrid System Techniques
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D033941:Clathrin Light Chains; D004268:DNA-Binding Proteins; C073368:HIP1 protein, human; C489534:Hip1r protein, mouse; D008840:Microfilament Proteins; D010446:Peptide Fragments; D033922:Clathrin Heavy Chains