FYVE domain found in hepatocyte growth factor (HGF)-regulated tyrosine kinase substrate (Hrs) and similar proteins
Hrs, also termed protein pp110, is a tyrosine phosphorylated protein that plays an important role in the signaling pathway of HGF. It is localized to early endosomes and an essential component of the endosomal sorting and trafficking machinery. Hrs interacts with hypertonia-associated protein Trak1, a novel regulator of endosome-to-lysosome trafficking. It can also forms an Hrs/actinin-4/BERP/myosin V protein complex that is required for efficient transferrin receptor (TfR) recycling but not for epidermal growth factor receptor (EGFR) degradation. Moreover, Hrs, together with STAM proteins, STAM1 and STAM2, and EPs15, forms a multivalent ubiquitin-binding complex that sorts ubiquitinated proteins into the multivesicular body pathway, and plays a regulatory role in endocytosis/exocytosis. Furthermore, Hrs functions as an interactor of the neurofibromatosis 2 tumor suppressor protein schwannomin/merlin. It is also involved in the inhibition of citron kinase-mediated HIV-1 budding. Hrs contains a single ubiquitin-interacting motif (UIM) that is crucial for its function in receptor sorting, and a FYVE domain that harbors double Zn2+ binding sites.