tyrosinebased

Tyrosinebased refers to motifs and signals in proteins that rely on a tyrosine residue to direct intracellular trafficking or signaling. In biology, tyrosine-based sorting signals are short cytoplasmic motifs that govern endocytosis and intracellular routing of transmembrane proteins through interactions with adaptor protein complexes and other cargo-recognition proteins.

Two common forms are the YXXΦ motif and the NPXY motif. In YXXΦ, a tyrosine (Y) is followed by any two amino acids (XX) and a bulky hydrophobic residue (Φ). In NPXY, an asparagine-proline pair is followed by any residue (X) and a terminal tyrosine (Y). These motifs are concentrated in the cytoplasmic tails of various receptors and transporters and function as contact points for adaptor proteins that help recruit clathrin or other trafficking machinery.

Recognition of tyrosine-based motifs is mediated by adaptor protein complexes such as AP-2 at the plasma membrane and AP-1/AP-3 in the trans-Golgi network and endosomes, enabling clathrin-coated vesicle formation and cargo sorting. Some NPXY motifs are recognized by PTB-domain–containing adaptors, linking receptor internalization to broader signaling and trafficking pathways. The presence and integrity of these motifs influence receptor downregulation, recycling, and downstream signaling.

Regulation can occur via phosphorylation of nearby residues, which may enhance or disrupt adaptor binding and alter trafficking outcomes. Tyrosine-based signals are contrasted with other sorting signals, such as di-leucine motifs, but together they form a key framework for intracellular protein sorting and regulation.