Endofin, also termed zinc finger FYVE domain-containing protein 16 (ZFY16), or endosome-associated FYVE domain protein, is a FYVE domain-containing protein that is localized to EEA1-containing endosomes. It is regulated by phosphoinositol lipid and engaged in endosome-mediated receptor modulation. Endofin is involved in Bone morphogenetic protein (BMP) signaling through interacting with Smad1 preferentially and enhancing Smad1 phosphorylation and nuclear localization upon BMP stimulation. It also functions as a scaffold protein that brings Smad4 to the proximity of the receptor complex in Transforming growth factor (TGF)-beta signaling. Moreover, endofin is a novel tyrosine phosphorylation target downstream of epidermal growth factor receptor (EGFR) in EGF-signaling. In addition, endofin plays a role in endosomal trafficking by recruiting cytosolic TOM1, an important molecule for membrane recruitment of clathrin, onto endosomal membranes.
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