Probable transporter, its natural substrate has not been found yet. May have a role in macrophage lipid metabolism and neural development. May play a role in myelination, perhaps as a transporter for certain kinds of myelin chemical components (PubMed:12210128). May play an important role in gamma-secretase processing of APP and thus in amyloid-beta peptide generation (PubMed:22086926). Regulates esterification of plasma membrane cholesterol by modulation of sphingolipid metabolism (PubMed:24201375). Probable lipid transporter that modulates cholesterol sequestration in the late endosome/lysosome by regulating the intracellular sphingolipid metabolism, in turn participates in cholesterol homeostasis (PubMed:24201375). May alter the transbilayer distribution of ceramide in the intraluminal membrane lipid bilayer, favoring its retention in the outer leaflet that results in increased acid ceramidase activity in the late endosome/lysosome, facilitating ceramide deacylation to sphingosine leading to the sequestration of free cholesterol in lysosomes (By similarity). In addition regulates amyloid-beta production either by activating a signaling pathway that regulates amyloid precursor protein transcription through the modulation of sphingolipid metabolism or through its role in gamma-secretase processing of APP (PubMed:22086926). May play a role in myelin formation (PubMed:12210128). Forms discrete, punctate intracellular vesicles. Expressed at high levels in brain, at moderate levels in heart, kidney and lung, and at low levels in skeletal muscle, stomach, spleen, colon and pancreas (PubMed:10970803). Not detected in the liver or small intestine (PubMed:10970803). In brain, highly expressed in white matter and detected in oligodendrocytes (PubMed:10970803, PubMed:11157071). Expressed in cerebellum as well as the anterior commissure (PubMed:11157071). Expressed mainly in the white matter but is also scattered in gray matter throughout the whole brain (PubMed:11157071). Expressed in myelinating cells of both ventral and dorsal restricted regions in newborn spinal cord (PubMed:12210128). Expressed in non-myelin-forming as well as in myelin-forming Schwann cells in the sciatic nerve (PubMed:17240058). N-glycosylated. Methylated at Gln-271 by N6AMT1. Belongs to the ABC transporter superfamily. ABCA family.