NPC1 and Niemann-Pick disease: Defects of NPC1 areassociated with hereditary Niemann–Pick disease leading toa fatal accumulation of low-density lipoprotein (LDL)-derived cholesterol.616 Active as a monomer with 13 TM helices andan extended N-terminal domain, NPC1 presumably acts as a receptor/transporterfor the cholesterol-loaded NPC2 soluble carrier via the N-terminalsoluble loop.274,586 It is also the target of theEbola virus acting as an intracellular receptor.