title: Splice variants of intersectin are components of the endocytic machinery in neurons and nonneuronal cells.
abstract: We recently identified and cloned intersectin, a protein containing two Eps15 homology (EH) domains and five Src homology 3 (SH3) domains. Using a newly developed intersectin antibody, we demonstrate that endogenous COS-7 cell intersectin localizes to clathrin-coated pits, and transfection studies suggest that the EH domains may direct this localization. Through alternative splicing in a stop codon, a long form of intersectin is generated with a C-terminal extension containing Dbl homology (DH), pleckstrin homology (PH), and C2 domains. Western blots reveal that the long form of intersectin is expressed specifically in neurons, whereas the short isoform is expressed at lower levels in glia and other nonneuronal cells. Immunofluorescence analysis of cultured hippocampal neurons reveals that intersectin is found at the plasma membrane where it is co-localized with clathrin. Ibp2, a protein identified based on its interactions with the EH domains of intersectin, binds to clathrin through the N terminus of the heavy chain, suggesting a mechanism for the localization of intersectin at clathrin-coated pits. Ibp2 also binds to the clathrin adaptor AP2, and antibodies against intersectin co-immunoprecipitate clathrin, AP2, and dynamin from brain extracts. These data suggest that the long and short forms of intersectin are components of the endocytic machinery in neurons and nonneuronal cells.
authors.affiliation: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, H3A 2B4, Canada.
authors.forename: N K
authors.initials: NK
authors.lastname: Hussain
authors.forename: M
authors.initials: M
authors.lastname: Yamabhai
authors.forename: A R
authors.initials: AR
authors.lastname: Ramjaun
authors.forename: A M
authors.initials: AM
authors.lastname: Guy
authors.forename: D
authors.initials: D
authors.lastname: Baranes
authors.forename: J P
authors.initials: JP
authors.lastname: O'Bryan
authors.forename: C J
authors.initials: CJ
authors.lastname: Der
authors.forename: B K
authors.initials: BK
authors.lastname: Kay
authors.forename: P S
authors.initials: PS
authors.lastname: McPherson
mesh_terms: D033962:Adaptor Protein Complex 2; D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D017398:Alternative Splicing; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism; D003001:Cloning, Molecular; D003034:Coated Pits, Cell-Membrane / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D034281:Dynamins; D004705:Endocytosis / Q000235:genetics*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D015870:Gene Expression; D006624:Hippocampus / Q000378:metabolism; D008565:Membrane Proteins; D009474:Neurons / Q000378:metabolism*; D010940:Plant Proteins; D051381:Rats; D014982:Xenopus laevis; D018909:src Homology Domains / Q000235:genetics
chemical_list: D033962:Adaptor Protein Complex 2; D033965:Adaptor Protein Complex alpha Subunits; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D002966:Clathrin; D004268:DNA-Binding Proteins; C088758:IBP2 protein, Zea mays; D008565:Membrane Proteins; D010940:Plant Proteins; C115919:intersectin 1; D020558:GTP Phosphohydrolases; D034281:Dynamins