ATP Binding Cassette Transporter G3 (ABCG3)

ABCG3 closely related to the multidrug transporter ABCG2 (MXR/ABCP) has an unusual ATP-binding domain. The ATP binding cassette (ABC) superfamily of membrane transporters is one of the largest protein classes known, and counts for numerous proteins involved in trafficking of biological molecules across membranes, host-defense mechanism to xenobiotics. In addition, increasing numbers of ABC proteins have recently been identified. ABCG2 has been identified as a candidate protein responsible for cancer multidrug resistance, the overexpression of ABCG2 was found in several drug-selective cell lines. Search made of EST databases with BLAST program led to identification of several mouse and rat sequences that had high homology to ABCG2 but that appeared to encode a unique gene. ABCG3 is the most closely related to ABCG2 with 54% amino acid identity overall.