The NPC1 protein is embedded in the membrane of the late endosome and lysosome, where it facilitates the egress of cholesterol and other lipids from these organelles. This function is crucial for maintaining lipid balance within cells. When NPC1 is dysfunctional, lipids accumulate within the lysosome, causing cellular toxicity and contributing to the pathophysiology of Niemann-Pick disease type C. This accumulation can also trigger a cascade of cellular events that might alter the cell's response to various toxins.
