ATP-dependent transporter of the ATP-binding cassette (ABC) family that actively extrudes physiological compounds, and xenobiotics from cells. Participates in physiological processes involving bile acids, conjugated steroids and cyclic nucleotides (, ). Stimulates the ATP-dependent uptake of a range of physiological lipophilic anions, including the glutathione S-conjugates leukotriene C4 and dinitrophenyl S-glutathione, steroid sulfates such as dehydroepiandrosterone 3-sulfate (DHEAS) and estrone 3-sulfate, glucuronides such as estradiol 17-beta-D-glucuronide (E(2)17betaG), the monoanionic bile acids glycocholate and taurocholate, and methotrexate (, ). Enhances also the cellular extrusion of cAMP and cGMP (, ). Confers resistance to anticancer drugs, such as 5-fluorouracil (5-FU) and methotrexate ( ). Probably functions to secrete earwax (, ). Required for the secretion of components contributing to axillary odor formation (  , ).
Subcellular locations: Cell membrane, Vacuole membrane, Cytoplasmic vesicle membrane, Apical cell membrane
Expressed in ceruminous apocrine gland (at protein level) (, ). Expressed in many tissues. Not expressed in kidney, spleen and colon. Highly expressed in breast cancer. Expressed at moderate levels in normal breast and testis and at very low levels in liver, brain and placenta ( , ). Localizes to axons of the CNS and peripheral nervous system (at protein level) .