Dual engagement regulation of protein interactions with the AP-2 adaptor alpha appendage.
Clathrin-mediated endocytosis depends upon the coordinated assembly of a large number of discrete clathrin coat components to couple cargo selection with rapid internalization from the cell surface. Accordingly, the heterotetrameric AP-2 adaptor complex binds not only to clathrin and select cargo molecules, but also to an extensive family of endocytic accessory factors and alternate sorting adaptors. Physical associations between accessory proteins and AP-2 occur primarily through DP(F/W) or FXDXF motifs, which engage an interaction surface positioned on the C-terminal platform subdomain of the independently folded alpha subunit appendage. Here, we find that the WXX(F/W)X(D/E) interaction motif found in several endocytic proteins, including synaptojanin 1, stonin 2, AAK1, GAK, and NECAP1, binds a second interaction site on the bilobal alpha appendage, located on the N-terminal beta sandwich subdomain. Both alpha appendage binding sites can be engaged synchronously, and our data reveal that varied assemblies of interaction motifs with different affinities for two sites upon the alpha appendage can provide a mechanism for temporal ordering of endocytic accessory proteins during clathrin-mediated endocytosis.
Mishra
Sanjay K
SK
Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
Hawryluk
Matthew J
MJ
Brett
Tom J
TJ
Keyel
Peter A
PA
Dupin
Amie L
AL
Jha
Anupma
A
Heuser
John E
JE
Fremont
Daved H
DH
Traub
Linton M
LM
D033962:Adaptor Protein Complex 2 / Q000737:chemistry*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002966:Clathrin / Q000502:physiology; D004705:Endocytosis; D008969:Molecular Sequence Data; D010802:Phylogeny; D021122:Protein Subunits; D051381:Rats
D033962:Adaptor Protein Complex 2; D002966:Clathrin; D021122:Protein Subunits