Which of the following is TRUE about AP (adapter protein) complexes?
Heterotetrameric adapter protein complexes link cargo sorting signals to clathrin and other coats decoding destinations. AP2 composed of alpha, beta2, mu2, sigma2 about 300 kDa localizes exclusively to plasma membrane where alpha appendage ear binds PIP2 and accessory proteins Eps15 and epsin. Mu2 middle domain recognizes YXXPhi tyrosine signals where tyrosine sits in deep hydrophobic pocket and phi bulky hydrophobic; affinity enhanced by phosphorylation at Thr156 by AAK1 kinase upon membrane recruitment. Dileucine [DE]XXXL[LI] also recognized. Transferrin receptor YTRF, LDL receptor FXNPXY vi
Ref: Robinson, Trends Cell Biol 2015: AP2 adaptor complex in clathrin-mediated endocytosis at plasma membrane.
