Identification of a family of endocytic proteins that define a new alpha-adaptin ear-binding motif.
Endocytosis by clathrin-coated vesicles (CCVs) is an important mechanism mediating protein internalization. Here, we show that two proteins identified through a proteomics analysis of CCVs are new components of the endocytic machinery. The proteins, named NECAP (adaptin-ear-binding coat-associated protein) 1 and 2, are paralogues that display no sequence similarity or common domains with any known protein. Both are enriched in CCV coats, and further analysis of the brain-enriched isoform, NECAP 1, shows its partial localization to clathrin-coated pits and direct binding to the globular ear domain of the alpha-adaptin subunit (alpha-ear) of the adaptor protein 2 (AP-2) complex. Intriguingly, this interaction is mediated by a new motif, WVQF, that uses a distinct alpha-ear interface relative to known alpha-ear-binding partners. Disruption of this interaction blocks clathrin-mediated endocytosis. Together, our studies identify a new family of endocytic proteins that define a unique AP-2-binding motif.
Ritter
Brigitte
B
Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4.
Philie
Jacynthe
J
Girard
Martine
M
Tung
Elaine C
EC
Blondeau
Francois
F
McPherson
Peter S
PS
D033965:Adaptor Protein Complex alpha Subunits / Q000235:genetics; D020816:Amino Acid Motifs / Q000235:genetics* / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D022163:Clathrin-Coated Vesicles / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics* / Q000502:physiology
D033965:Adaptor Protein Complex alpha Subunits; D008565:Membrane Proteins; C487984:NECAP1 protein, rat; C487985:NECAP2 protein, rat; D011506:Proteins