INTERACTION OF TYROSINE-BASED SORTING SIGNALS WITH CLATHRIN-ASSOCIATED PROTEINS

Tyrosine-based signals within the cytoplasmic domain of integral membr ane proteins mediate clathrin-dependent protein sorting in the endocyt ic and secretory pathways. A yeast two-hybrid system was used to ident ify proteins that bind to tyrosine-based signals. The medium chains (m u(1) and mu(2)) of two clathrin-associated protein complexes (AP-1 and AP-2, respectively) specifically interacted with tyrosine-based signa ls of several integral membrane proteins. The interaction was confirme d by in vitro binding assays. Thus, it is likely that the medium chain s serve as signal-binding components of the clathrin-dependent sorting machinery.