YxxLI
YxxLI is a short linear motif described in the cytoplasmic tails of certain transmembrane proteins. It represents a variant of the well-known tyrosine-based sorting motif YxxØ, where Y is tyrosine, x is any residue, and Ø is a bulky hydrophobic residue. In the YxxLI variant, the sequence matches tyrosine followed by any two residues and then leucine (L) and isoleucine (I). The motif is implicated in trafficking signals that can mediate recognition by clathrin adaptor protein complexes (such as AP-1, AP-2, and AP-3) and the assembly of clathrin-coated vesicles, thereby influencing endocytosis and intracellular sorting.
Function and context: Recognition of YxxLI is context-dependent. Binding to adaptor complexes can promote internalization from
Occurrence and examples: YxxLI is not universal but has been reported in a subset of cargo proteins
Research and methods: Identification typically involves sequence analysis to detect the motif, followed by mutational studies
See also: tyrosine-based sorting motif; YxxØ; clathrin-mediated endocytosis; adaptor protein complexes.