Molecular switches involving the AP-2 beta2 appendage regulate endocytic cargo selection and clathrin coat assembly.
Clathrin-associated sorting proteins (CLASPs) expand the repertoire of endocytic cargo sorted into clathrin-coated vesicles beyond the transmembrane proteins that bind physically to the AP-2 adaptor. LDL and GPCRs are internalized by ARH and beta-arrestin, respectively. We show that these two CLASPs bind selectively to the AP-2 beta2 appendage platform via an alpha-helical [DE](n)X(1-2)FXX[FL]XXXR motif, and that this motif also occurs and is functional in the epsins. In beta-arrestin, this motif maintains the endocytosis-incompetent state by binding back on the folded core of the protein in a beta strand conformation. Triggered via a beta-arrestin/GPCR interaction, the motif must be displaced and must undergo a strand to helix transition to enable the beta2 appendage binding that drives GPCR-beta-arrestin complexes into clathrin coats. Another interaction surface on the beta2 appendage sandwich is identified for proteins such as eps15 and clathrin, suggesting a mechanism by which clathrin displaces eps15 to lattice edges during assembly.
Edeling
Melissa A
MA
Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 2XY, United Kingdom.
Mishra
Sanjay K
SK
Keyel
Peter A
PA
Steinhauser
Amie L
AL
Collins
Brett M
BM
Roth
Robyn
R
Heuser
John E
JE
Owen
David J
DJ
Traub
Linton M
LM
D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D019390:Arrestins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002966:Clathrin / Q000378:metabolism*; D022163:Clathrin-Coated Vesicles / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004705:Endocytosis / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D011973:Receptors, LDL / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D050656:Transcription Factor AP-2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism; D000071557:beta-Arrestins
D033942:Adaptor Proteins, Vesicular Transport; D019390:Arrestins; D002966:Clathrin; D010455:Peptides; D043562:Receptors, G-Protein-Coupled; D011973:Receptors, LDL; D011993:Recombinant Fusion Proteins; D050656:Transcription Factor AP-2; D033921:Vesicular Transport Proteins; D000071557:beta-Arrestins; C114154:epsin