ATP-binding cassette subfamily G member 2 (ABCG2) is a eukaryotic member of the ABC transporter family. In humans, ABCG2 is a high-capacity urate exporter, functioning in both renal and extrarenal urate excretion []. It is a major factor contributing to gout [, ]. It also coordinates with another transporter, ABCB6, to modulate porphyrin concentrations under normal physiological and pathological conditions []. In addition, it can function as a xenobiotic transporter and may play a major role in multi-drug resistance []. The ABC transporter family is a group of membrane proteins that use the hydrolysis of ATP to power the translocation of a wide variety of substrates across cellular membranes. ABC transporters minimally consist of two conserved regions: a highly conserved nucleotide-binding domain (NBD) and a less conserved transmembrane domain (TMD). Eukaryotic ABC proteins are usually organised either as full transporters (containing two NBDs and two TMDs), or as half transporters (containing one NBD and one TMD), that have to form homo- or heterodimers in order to constitute a functional protein [].
