ATP-dependent transporter of the ATP-binding cassette (ABC) family which transports various molecules including bioamines, neurotransmitters and metabolic intermediates (PubMed:117796, PubMed:8144619, PubMed:10407069, PubMed:18931318, PubMed:33820991). In the eye and probably in association with w/white, required for the transport of the eye red pigment precursor, guanine, into pigment cell granules (PubMed:8144619, PubMed:117796). In Malpighian tubules, involved in guanine uptake (PubMed:117796). Probably in association with w/white, involved in aging-induced intestinal stem cell proliferation in the midgut by regulating tetrahydrofolate transport (PubMed:33820991). ATP + guanine(out) + H2O = ADP + guanine(in) + H(+) + phosphate ATP + H2O + riboflavin(in) = ADP + H(+) + phosphate + riboflavin(out) (6S)-5,6,7,8-tetrahydrofolate(out) + ATP + H2O = (6S)-5,6,7,8-tetrahydrofolate(in) + ADP + H(+) + phosphate May form a heterodimer with w/white. Up-regulated during aging in intestinal stem cells. Eyes are brown due to a defect in red pigment production (PubMed:10407069). In Malpighian tubules, guanine uptake is impaired (PubMed:117796). Reduces the levels of several metabolites, including kynurenine, kynurenic acid, 3-hydroxykynurenine, guanosine, xanthine, urate, riboflavin, and tetrahydrofolate, and increases the levels of guanine (PubMed:33820991). In the head, levels of neurotransmitters histamine, dopamine and serotonin are reduced; specifically, histamine is reduced in the retina (PubMed:18931318). Severe loss of white protein in the retina lamina and photoreceptors (PubMed:18931318). In addition, in lamina photoreceptor terminals R1-R6, number of synaptic vesicles is reduced (PubMed:18931318). Inhibits aging-induced intestinal stem cell proliferation (PubMed:33820991). Belongs to the ABC transporter superfamily. ABCG family. Eye pigment precursor importer (TC 3.A.1.204) subfamily. Probable cloning artifact.