MEDIUM CHAINS OF ADAPTER COMPLEXES AP-1 AND AP-2 RECOGNIZE LEUCINE-BASED SORTING SIGNALS FROM THE INVARIANT CHAIN

Interactions between tyrosine-and leucine-based sorting signals in the cytoplasmic tails of transmembrane proteins and adaptor complexes AP- 1 and AP-2 are believed to be the first step in the formation of clath rin-coated vesicles that deliver these proteins to their destination. Medium chains of AP-1 and AP-2 have been reported to interact with tyr osine-based sorting signals in a number of in vitro assays. In the pre sent study we found that recombinant medium chains could interact with leucine-based sorting signals from the cytoplasmic tail of the invari ant chain. Medium chains may therefore be responsible for the proper r ecognition of both tyrosine and leucine sorting signals by AP-1 and AP -2 complexes.