Chaperone specifically assisting the folding of beta-propeller/EGF modules within the family of low-density lipoprotein receptors (LDLRs). Acts as a modulator of the Wnt pathway through chaperoning the coreceptors of the canonical Wnt pathway, LRP5 and LRP6, to the plasma membrane. Essential for specification of embryonic polarity and mesoderm induction. Plays an essential role in neuromuscular junction (NMJ) formation by promoting cell-surface expression of LRP4. May regulate phagocytosis of apoptotic retinal pigment epithelium (RPE) cells.
Subcellular locations: Endoplasmic reticulum
Released from apoptotic cells and shed photoreceptor outer segments (By similarity).