This chapter will describe function and expression of several ABC transporters (such as P-GP, BCRP, and MRPs), their substrates and inhibitors, as well as their clinical significance.ĪBC gene-related disease Breast cancer resistance protein Multidrug resistance Multidrug resistance-associated proteins P-glycoprotein. ABC transporters are typically single polypeptide chains that consist of a transmembrane domain (TMD), a nucleotide-binding domain (NBD), followed by another TMD and NBD (see chapter, ABC Transporters: An Overview ). Several of them are central to phenomena of biomedical interest, including cystic fibrosis and resistance to chemotherapeutic drugs. Several human diseases such as cystic fibrosis, sitosterolemia, Tangier disease, intrahepatic cholestasis, and retinal degeneration are associated with mutations in corresponding transporters. ATP-binding cassette (ABC) transporters are membrane-bound molecular pumps that form one of the largest of all protein families. Some ABC transporters are also involved in diverse cellular processes such as maintenance of osmotic homeostasis, antigen processing, cell division, immunity, cholesterol, and lipid trafficking. These ABC transporters are expressed in various tissues such as the liver, intestine, kidney, and brain, playing important roles in absorption, distribution, and excretion of drugs. Of them, at least 11 ABC transporters including P-glycoprotein (P-GP/ABCB1), multidrug resistance-associated proteins (MRPs/ABCCs), and breast cancer resistance protein (BCRP/ABCG2) are involved in multidrug resistance (MDR) development. Characterization of the conformation landscape of the bacterial ABC transporter CydDC reveals that this heterodimeric protein complex is a long-sought heme transporter essential for the functional. ATP-binding cassette (ABC) transporters are ubiquitous membrane proteins that couple the transport of diverse substrates across cellular membranes to the. The two halves of the protein, each containing a transmembrane domain (TMD) and an ATP-binding cassette, are separated by a characteristic hydrophobic loop ( HH1, arrow) that dips into the membrane. More than 40 ABC transporters have been identified in human, which are divided into 7 subfamilies (ABCA to ABCG) based on their gene structure, amino acid sequence, domain organization, and phylogenetic analysis. Gene ( a) and protein ( b) structures of ABC transporters included in the A-subfamily. ABC transporter permease protein NatB Curated Alternative names ABC-type Na (+) transporter. One of the largest transporter families is the ATP-binding cassette (ABC) family. ABCB6 is a half-transporter that contains a single pair of TMD and NBD, but needs to form a. ![]() The processes are usually mediated by specific transporters. ABCB6 is an 842-amino acid protein that belongs to the B subfamily of the ABC transporter. The transport of specific molecules across lipid membranes is an essential function of all living organisms. A controversial issue in the ABC transporter field is whether the transmembrane components contain a well-defined substrate-binding site.
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