Intracellular cholesterol transporter which acts in concert with NPC1 and plays an important role in the egress of cholesterol from the lysosomal compartment (PubMed:29580834, PubMed:17552909). Unesterified cholesterol that has been released from LDLs in the lumen of the late endosomes/lysosomes is transferred by NPC2 to the cholesterol-binding pocket in the N-terminal domain of NPC1 (By similarity). May bind and mobilize cholesterol that is associated with membranes (PubMed:18823126). NPC2 binds cholesterol with a 1:1 stoichiometry (PubMed:17573352). Can bind a variety of sterols, including lathosterol, desmosterol and the plant sterols stigmasterol and beta-sitosterol (By similarity). The secreted form of NCP2 regulates biliary cholesterol secretion via stimulation of ABCG5/ABCG8-mediated cholesterol transport (By similarity). cholesterol(in) = cholesterol(out) Interacts with NPC1 (via the second lumenal domain) in a cholestrol-dependent manner (PubMed:22065762, PubMed:27551080). Interacts with NUS1/NgBR, the interaction stabilizes NCP2 and regulates cholesterol trafficking. Interacts with DHDDS. Interacts with NEDD4L (via C2 domain). Interacts with NPC1L1 (By similarity). Interaction with cell-surface M6PR mediates endocytosis and targeting to lysosomes. Expressed in kidney, spleen, liver and mammary gland, but not in testis. Binds cholesterol in a hydrophobic pocket; there are no hydrogen bonds between the sterol and the protein. Belongs to the NPC2 family.