Catalyzes the efflux of phospholipids such as sphingomyelin, cholesterol and its oxygenated derivatives like 7beta-hydroxycholesterol and this transport is coupled to hydrolysis of ATP (PubMed:14668945). The lipid efflux is ALB-dependent. Is an active component of the macrophage lipid export complex. Could also be involved in intracellular lipid transport processes. The role in cellular lipid homeostasis may not be limited to macrophages. Prevents cell death by transporting cytotoxic 7beta-hydroxycholesterol (By similarity). 7beta-hydroxycholesterol(in) + ATP + H2O = 7beta-hydroxycholesterol(out) + ADP + H(+) + phosphate ATP + cholesterol(in) + H2O = ADP + cholesterol(out) + H(+) + phosphate an N-(acyl)-sphingosylphosphocholine(in) + ATP + H2O = ADP + an N-(acyl)-sphingosylphosphocholine(out) + H(+) + phosphate a sphingomyelin(in) + ATP + H2O = a sphingomyelin(out) + ADP + H(+) + phosphate The cholesterol efflux is enhanced by APOA1. Homodimer; disulfide-linked. Homooligomer. May form heterodimers with several heterologous partners of the ABCG subfamily. Forms heterodimers with ABCG4. Interacts with CAV1; this interaction regulates ABCG1-mediated cholesterol efflux. Predominantly localized in the intracellular compartments mainly associated with the endoplasmic reticulum (ER) and Golgi membranes. Expressed mainly in brain, thymus, lung, adrenals, spleen and placenta. Little or no expression in liver, kidney, heart, muscle or testes. Strongly induced in macrophage cell line RAW 264.7 during cholesterol influx. Induction is mediated by the liver X receptor/retinoid X receptor (LXR/RXR) pathway. Down-regulated by endotoxins or cytokines (TNF and IL1) in J-774 macrophages. Palmitoylation at Cys-315 seems important for trafficking from the endoplasmic reticulum. Belongs to the ABC transporter superfamily. ABCG family. Eye pigment precursor importer (TC 3.A.1.204) subfamily.