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 evidences; 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 .
Subcellular locations: Late endosome membrane
Localizes to contact sites between the endoplasmic reticulum and late endosomes: associates with the endoplasmic reticulum membrane via interaction with VAPA, VAPB or MOSPD2.
Expressed in retina.