ATP-dependent transporter of the ATP-binding cassette (ABC) family that actively extrudes physiological compounds and xenobiotics from cells. Transports a range of endogenous molecules that have a key role in cellular communication and signaling, including cyclic nucleotides such as cyclic AMP (cAMP) and cyclic GMP (cGMP), bile acids, steroid conjugates, urate, and prostaglandins. Mediates also the ATP-dependent efflux of glutathione conjugates such as leukotriene C4 (LTC4) and leukotriene B4 (LTB4). The presence of GSH is necessary for the ATP-dependent transport of LTB4, whereas GSH is not required for the transport of LTC4. Mediates the cotransport of bile acids with reduced glutathione (GSH). Transports a wide range of drugs and their metabolites, including anticancer, antiviral and antibiotics molecules (Probable). Confers resistance to anticancer agents (Probable). ATP + H2O + xenobioticSide 1 = ADP + phosphate + xenobioticSide 2. an S-substituted glutathione(in) + ATP + H2O = ADP + an S-substituted glutathione(out) + H(+) + phosphate 17beta-estradiol 17-O-(beta-D-glucuronate)(in) + ATP + H2O = 17beta-estradiol 17-O-(beta-D-glucuronate)(out) + ADP + H(+) + phosphate ATP + dehydroepiandrosterone 3-sulfate(in) + H2O = ADP + dehydroepiandrosterone 3-sulfate(out) + H(+) + phosphate ATP + H2O + leukotriene C4(in) = ADP + H(+) + leukotriene C4(out) + phosphate ATP + H2O + leukotriene B4(in) = ADP + H(+) + leukotriene B4(out) + phosphate ATP + H2O + urate(in) = ADP + H(+) + phosphate + urate(out) 3',5'-cyclic GMP(in) + ATP + H2O = 3',5'-cyclic GMP(out) + ADP + H(+) + phosphate 3',5'-cyclic AMP(in) + ATP + H2O = 3',5'-cyclic AMP(out) + ADP + H(+) + phosphate ATP + H2O + prostaglandin E2(in) = ADP + H(+) + phosphate + prostaglandin E2(out) ATP + H2O + prostaglandin E1(in) = ADP + H(+) + phosphate + prostaglandin E1(out) ATP + glutathione(in) + glycodeoxycholate(in) + H2O = ADP + glutathione(out) + glycodeoxycholate(out) + H(+) + phosphate ATP + cholate(in) + glutathione(in) + H2O = ADP + cholate(out) + glutathione(out) + H(+) + phosphate ATP + glutathione(in) + glycocholate(in) + H2O = ADP + glutathione(out) + glycocholate(out) + H(+) + phosphate ATP + glutathione(in) + H2O + taurocholate(in) = ADP + glutathione(out) + H(+) + phosphate + taurocholate(out) ATP + glutathione(in) + glycochenodeoxycholate(in) + H2O = ADP + glutathione(out) + glycochenodeoxycholate(out) + H(+) + phosphate ATP + glutathione(in) + H2O + taurochenodeoxycholate(in) = ADP + glutathione(out) + H(+) + phosphate + taurochenodeoxycholate(out) ATP + glutathione(in) + glycoursodeoxycholate(in) + H2O = ADP + glutathione(out) + glycoursodeoxycholate(out) + H(+) + phosphate ATP + glutathione(in) + H2O + tauroursodeoxycholate(in) = ADP + glutathione(out) + H(+) + phosphate + tauroursodeoxycholate(out) Interacts (via PDZ-binding motif) with SNX27 (via PDZ domain); this interaction accelerates MRP4 internalization. Its localization to the basolateral or apical membranes is tissue-dependent. Ubiquitously expressed across all developmental stages. N-glycosylated; leading to substrate-selective effects on its transport activity. Homozygous null mice are viable and fertile and exhibit any overt phenotype under normal conditions. However deficient mice show impaired anion transport in the blood-brain and blood-cerebrospinal fluid barriers and kidney. Deficient mice show an accumulation of the anticancer agent topotecan in brain and cerebrospinal fluid (CSF) (PubMed:15314169). In addition, penetration of PMEA, an antiviral agent, into the brain is increased in deficient mice (PubMed:17210706).