ATP-binding cassette domain of multidrug resistance protein-like transporters
The MRP (Multidrug Resistance Protein)-like transporters are involved in drug, peptide, and lipid export. They belong to the subfamily C of the ATP-binding cassette (ABC) superfamily of transport proteins. The ABCC subfamily contains transporters with a diverse functional spectrum that includes ion transport, cell surface receptor, and toxin secretion activities. The MRP-like family, similar to all ABC proteins, have a common four-domain core structure constituted by two membrane-spanning domains, each composed of six transmembrane (TM) helices, and two nucleotide-binding domains (NBD). ABC transporters are a subset of nucleotide hydrolases that contain a signature motif, Q-loop, and H-loop/switch region, in addition to, the Walker A motif/P-loop and Walker B motif commonly found in a number of ATP- and GTP-binding and hydrolyzing proteins.