Regulates the composition and fluidity of the plasma membrane (By similarity). Inhibits the incorporation of membrane-fluidizing phospholipids containing omega-3 long-chain polyunsaturated fatty acids (LCPUFA) and thereby promotes membrane rigidity (By similarity). Does not appear to have any effect on LCPUFA synthesis (By similarity). Was originally proposed to be a calcium channel facilitator (By similarity). However, a more recent study shows that this protein regulates membrane phospholipid homeostasis (By similarity). Therefore, any effects on calcium flux are most likely a secondary consequence of defects in membrane composition or fluidity (By similarity).