Intracellular cholesterol transporter which acts in concert with NPC1 and plays an important role in the egress of cholesterol from the lysosomal compartment. 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. May bind and mobilize cholesterol that is associated with membranes. NPC2 binds cholesterol with a 1:1 stoichiometry. 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. Interacts with NUS1/NgBR, the interaction stabilizes NCP2 and regulates cholesterol trafficking. Interacts with DHDDS. Interacts with NEDD4L (via C2 domain). Interacts with NPC1L1. Interaction with cell-surface M6PR mediates endocytosis and targeting to lysosomes. Epididymis. High levels are found in the caput and corpus regions. Weaker levels in the distal cauda and in the efferent ducts. Binds cholesterol in a hydrophobic pocket; there are no hydrogen bonds between the sterol and the protein. Belongs to the NPC2 family.