STARD3

Sterol-binding protein that mediates cholesterol transport from the endoplasmic reticulum to endosomes. The sterol transport mechanism is triggered by phosphorylation of FFAT motif that leads to membrane tethering between the endoplasmic reticulum and late endosomes via interaction with VAPA and VAPB. Acts as a lipid transfer protein that redirects sterol to the endosome at the expense of the cell membrane and favors membrane formation inside endosomes. May also mediate cholesterol transport between other membranes, such as mitochondria membrane or cell membrane. However, such results need additional experimental evidence; probably mainly mediates cholesterol transport from the endoplasmic reticulum to endosomes. Does not activate transcriptional cholesterol sensing. Able to bind other lipids, such as lutein, a xanthophyll carotenoids that form the macular pigment of the retina..

Function from UniProtKB (Q14849), read 2026-09-23. CC BY 4.0.