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A Screen for Endocytic Motifs
Author(s) -
Kozik Patrycja,
Francis Richard W.,
Seaman Matthew N. J.,
Robinson Margaret S.
Publication year - 2010
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2010.01056.x
Subject(s) - endocytic cycle , biology , endocytosis , internalization , microbiology and biotechnology , protein sorting signals , signal transducing adaptor protein , clathrin , peptide sequence , genetics , cell , signal peptide , gene , signal transduction
Sorting signals for cargo selection into coated vesicles are usually in the form of short linear motifs. Three motifs for clathrin‐mediated endocytosis have been identified: YXXΦ, [D/E]XXXL[L/I] and FXNPXY. To search for new endocytic motifs, we made a library of CD8 chimeras with random sequences in their cytoplasmic tails, and used a novel fluorescence‐activated cell sorting (FACS)‐based assay to select for endocytosed constructs. Out of the five tails that were most efficiently internalized, only one was found to contain a conventional motif. Two contain dileucine‐like sequences that appear to be variations on the [D/E]XXXL[L/I] motif. Another contains a novel internalization signal, YXXXΦN, which is able to function in cells expressing a mutant µ2 that cannot bind YXXΦ, indicating that it is not a variation on the YXXΦ motif. Similar sequences are present in endogenous proteins, including a functional YXXXΦN (in addition to a classical YXXΦ) in cytotoxic T‐lymphocyte‐associated protein 4 (CTLA‐4). Thus, the repertoire of endocytic motifs is more extensive than the three well‐characterized sorting signals.