HIP1 functions in clathrin-mediated endocytosis through binding to clathrin and adaptor protein 2.
Polyglutamine expansion in huntingtin is the underlying mutation leading to neurodegeneration in Huntington disease. This mutation influences the interaction of huntingtin with different proteins, including huntingtin-interacting protein 1 (HIP1), in which affinity to bind to mutant huntingtin is profoundly reduced. Here we demonstrate that HIP1 colocalizes with markers of clathrin-mediated endocytosis in neuronal cells and is highly enriched on clathrin-coated vesicles (CCVs) purified from brain homogenates. HIP1 binds to the clathrin adaptor protein 2 (AP2) and the terminal domain of the clathrin heavy chain, predominantly through a small fragment encompassing amino acids 276-335. This region, which contains consensus clathrin- and AP2-binding sites, functions in conjunction with the coiled-coil domain to target HIP1 to CCVs. Expression of various HIP1 fragments leads to a potent block of clathrin-mediated endocytosis. Our findings demonstrate that HIP1 is a novel component of the endocytic machinery.
Metzler
M
M
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada.
Legendre-Guillemin
V
V
Gan
L
L
Chopra
V
V
Kwok
A
A
McPherson
P S
PS
Hayden
M R
MR
D033962:Adaptor Protein Complex 2; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology*; D002460:Cell Line; D002966:Clathrin / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins; D004705:Endocytosis; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014168:Transferrin / Q000493:pharmacokinetics
D033962:Adaptor Protein Complex 2; D033942:Adaptor Proteins, Vesicular Transport; D000596:Amino Acids; D002352:Carrier Proteins; D002966:Clathrin; D004268:DNA-Binding Proteins; C073368:HIP1 protein, human; D008565:Membrane Proteins; D014168:Transferrin; D004247:DNA