Clathrin- and AP-2-binding sites in HIP1 uncover a general assembly role for endocytic accessory proteins.
Clathrin-mediated endocytosis is a major pathway for the internalization of macromolecules into the cytoplasm of eukaryotic cells. The principle coat components, clathrin and the AP-2 adaptor complex, assemble a polyhedral lattice at plasma membrane bud sites with the aid of several endocytic accessory proteins. Here, we show that huntingtin-interacting protein 1 (HIP1), a binding partner of huntingtin, copurifies with brain clathrin-coated vesicles and associates directly with both AP-2 and clathrin. The discrete interaction sequences within HIP1 that facilitate binding are analogous to motifs present in other accessory proteins, including AP180, amphiphysin, and epsin. Bound to a phosphoinositide-containing membrane surface via an epsin N-terminal homology (ENTH) domain, HIP1 associates with AP-2 to provide coincident clathrin-binding sites that together efficiently recruit clathrin to the bilayer. Our data implicate HIP1 in endocytosis, and the similar modular architecture and function of HIP1, epsin, and AP180 suggest a common role in lipid-regulated clathrin lattice biogenesis.
Mishra
S K
SK
Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
Agostinelli
N R
NR
Brett
T J
TJ
Mizukami
I
I
Ross
T S
TS
Traub
L M
LM
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001704:Biopolymers; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D008969:Molecular Sequence Data; D051381:Rats; D017386:Sequence Homology, Amino Acid; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000378:metabolism*
D001704:Biopolymers; D002352:Carrier Proteins; D002966:Clathrin; D004268:DNA-Binding Proteins; D050656:Transcription Factor AP-2; D014157:Transcription Factors