Function
Inhibits endoplasmic reticulum (ER) stress response (By similarity). Retained in the ER under normal conditions and is up-regulated and secreted by the ER in response to ER stress and hypoxia (By similarity). Following secretion by the ER, directly binds to 3-O-sulfogalactosylceramide, a lipid sulfatide in the outer cell membrane of target cells (PubMed:29497057). Sulfatide binding promotes its cellular uptake by endocytosis, and is required for its role in alleviating ER stress under ER stress conditions (By similarity). Has a neuroprotective role, ensuring survival of dopaminergic neurons during normal growth (PubMed:30147641).