Cholesterol efflux transporter in macrophages that is responsible for APOAI/high-density lipoproteins (HDL) formation at the plasma membrane under high cholesterol levels and participates in reverse cholesterol transport (PubMed:25125465, PubMed:32687853, PubMed:20382126). May play a role in the processing of autolysosomes (PubMed:15870284). ATP + cholesterol(in) + H2O = ADP + cholesterol(out) + H(+) + phosphate Localized at cell membrane under high cholesterol levels. Expressed in cardiomyocytes, oligodendrocytes and astrocytes in brain, alveolar type 2 cells in lung and follicular cells in the thyroid gland (at protein level). Detected in brain, testis, lung, heart, liver, kidney, skeletal muscle and placenta. Strongly expressed in the basal cells of the seminiferous tubules, interstitial cells consisting of Leydig cells, as well as the tunica albuginea (PubMed:24831815). In the epididymis, specificly and very strongly expressed in the connective tissue outlining the cylindrical epithelium in the corpus and cauda regions, including fibrocytes and smooth muscle cells, as well as within the basal and tall columnar cells of the corpus cylindrical epithelium (PubMed:24831815). Highly expressed in the brain with high expression in cortical and hippocampal neurons and moderately in the lung (PubMed:25125465). Expressed during embryogenesis. Down-regulated by digoxin (PubMed:16445568). Up-regulated by an excess cellular cholesterol level (PubMed:32687853). Up-regulated when ABCA1 is down-regulated (PubMed:32687853). N-glycosylated. Mice display hypothyroidism and lethal heart abnormalities that may be due to altered autolysosomes processing. Belongs to the ABC transporter superfamily. ABCA family.