Summary: Organic Anion Transporter Polypeptide (OATP) family
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Organic anion-transporting polypeptide Edit Wikipedia article
|Organic Anion Transporter Polypeptide (OATP) family|
An organic anion-transporting polypeptide (OATP) is a membrane transport protein or 'transporter' that mediates the transport of mainly organic anions across the cell membrane. Therefore OATPs are present in the lipid bilayer of the cell membrane, acting as the cell's gatekeepers. OATPs belong to the Solute Carrier Family (SLC), more specifically the Solute Carrier Organic Anion (SLCO) gene subfamily 
Organic anion transporting polypeptides carry bile acids as well as bilirubin and numerous hormones such as thyroid and steroid hormones across the basolateral membrane (facing sinusoids) in hepatocytes, for excretion in bile. As well as expression in the liver, OATPs are expressed in many other tissues on basolateral and apical membranes, transporting anions, as well as neutral and even cationic compounds. They also transport an extremely diverse range of drug compounds, ranging from anti-cancer, antibiotic, lipid lowering to anti-diabetic drugs, as well as toxins and poisons.
The table below shows the 11 known human OATPs. Note: Human OATPs are designated with capital letters, animal Oatps are designated with lower class letters. The 'SLCO' stands for their gene name; 'solute carrier organic anion.' Previous nomenclature using letters and numbers (e.g. OATP-A, OATP-8 is no longer correct. The most well characterised human OATPs are OATP1A2, OATP1B1, OATP1B3 and OATP2B1. Very little is known about the function and characteristics of OATP5A1 and OATP6A1.
|SLCO1A2||Solute carrier organic anion transporter family member 1A2||Ubiquitous|
|SLCO1B1||Solute carrier organic anion transporter family member 1B1||Liver|
|SLCO1B3||Solute carrier organic anion transporter family member 1B3||Liver|
|SLCO1C1||Solute carrier organic anion transporter family member 1C1||Brain, testis|
|SLCO2A1||Solute carrier organic anion transporter family member 2A1||Ubiquitous|
|SLCO2B1||Solute carrier organic anion transporter family member 2B1||Ubiquitous|
|SLCO3A1||Solute carrier organic anion transporter family member 3A1||Testis, brain, heart, lung, spleen|
|SLCO4A1||Solute carrier organic anion transporter family member 4A1||Heart, placenta, lung, liver|
|SLCO4C1||Solute carrier organic anion transporter family member 4C1||Kidney|
|SLCO5A1||Solute carrier organic anion transporter family member 5A1||Breast, fetal brain, prostate|
|SLCO6A1||Solute carrier organic anion transporter family member 6A1||Testes, spleen, brain, placenta|
The OATPs play a fundamental role in the transport of drugs across the cell membrane, particularly in the liver and kidney. In the liver, OATPs are expressed on the basolateral membrane of hepatocytes, transporting compounds into the hepatocyte for biotransformation. A number of drug-drug interactions have been associated with the OATPs, affecting the pharmacokinetics and pharmacodynamics of drugs. This is most commonly where one drug inhibits the transport of another drug into the hepatocyte, so that it is retained in the body. The OATPs most associated with these interactions are OATP1B1, OATP1B3 and OATP2B1, which are all present on the hepatocyte basolateral membrane. The most clinically relevant interactions have been associated with the lipid lowering drugs statins, which led to the removal of cerivastatin from the market in 2002. Single nucleotide polymorphisms (SNPs) are also associated with the OATPs; particularly OATP1B1, causing
It is likely that along with the Organic Anion Transporters, Organic Cation transporters and the ATP-binding cassette transporters, the OATPs play a central role in the absorption, distribution, metabolism and exretion (ADME) of drug compounds.
Oatps are present in many animals, including zebrafish, dog, cow, rat, mouse, monkey and horse. Oatps are not present in bacteria, indicating their evolution from the animal kingdom. However homologs do not correlate well with the human OATPs and therefore it is likely that isoforms arose by gene duplication. An Oatp has however been found in the little skate (Raja erinacea), suggesting that their evolution was early in the formation of the animal kingdom.
- Hagenbuch B, Meier PJ (February 2004). "Organic anion transporting polypeptides of the OATP/ SLC21 family: phylogenetic classification as OATP/ SLCO superfamily, new nomenclature and molecular/functional properties". Pflugers Arch. 447 (5): 653â65. doi:10.1007/s00424-003-1168-y. PMID 14579113.
- Pages 980-990 in:Walter F., PhD. Boron (2003). Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders. pp. 1300. ISBN 1-4160-2328-3.
- Price KL, Sautin YY, Long DA, Zhang L, Miyazaki H, Mu W, Endou H, Johnson RJ (July 2006). "Human vascular smooth muscle cells express a urate transporter". J. Am. Soc. Nephrol. 17 (7): 1791â5. doi:10.1681/ASN.2006030264. PMID 16775029.
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Organic Anion Transporter Polypeptide (OATP) family Provide feedback
This family consists of several eukaryotic Organic-Anion-Transporting Polypeptides (OATPs). Several have been identified mostly in human and rat. Different OATPs vary in tissue distribution and substrate specificity. Since the numbering of different OATPs in particular species was based originally on the order of discovery, similarly numbered OATPs in humans and rats did not necessarily correspond in function, tissue distribution and substrate specificity (in spite of the name, some OATPs also transport organic cations and neutral molecules). Thus, Tamai et al.  initiated the current scheme of using digits for rat OATPs and letters for human ones. Prostaglandin transporter (PGT) proteins (e.g. Q92959) are also considered to be OATP family members. In addition, the methotrexate transporter OATK (P70502) is closely related to OATPs. This family also includes several predicted proteins from Caenorhabditis elegans and Drosophila melanogaster. This similarity was not previously noted. Note: Members of this family are described (in the Swiss-Prot database) as belonging to the SLC21 family of transporters.
Tamai I, Nezu J, Uchino H, Sai Y, Oku A, Shimane M, Tsuji A; , Biochem Biophys Res Commun 2000;273:251-260.: Molecular identification and characterization of novel members of the human organic anion transporter (OATP) family. PUBMED:10873595 EPMC:10873595
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR004156
This family consists of several eukaryotic Organic-Anion-Transporting Polypeptides (OATPs). Several have been identified mostly in human and rat. Different OATPs vary in tissue distribution and substrate specificity. Since the numbering of different OATPs in particular species was based originally on the order of discovery, similarly numbered OATPs in humans and rats did not necessarily correspond in function, tissue distribution and substrate specificity (in spite of the name, some OATPs also transport organic cations and neutral molecules) so a scheme of using digits for rat OATPs and letters for human ones was introduced [PUBMED:10873595]. Prostaglandin transporter (PGT) proteins are also considered to be OATP family members. In addition, the methotrexate transporter OATK is closely related to OATPs. This family also includes several predicted proteins from Caenorhabditis elegans and Drosophila melanogaster. This similarity was not previously noted. Note: Members of this family are described (in the UniProtKB/Swiss-Prot database) as belonging to the SLC21 family of transporters.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||membrane (GO:0016020)|
|Molecular function||transporter activity (GO:0005215)|
|Biological process||transport (GO:0006810)|
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Curation and family details
|Seed source:||Pfam-B_626 (release 6.5)|
|Author:||Mifsud W, Bateman A|
|Number in seed:||16|
|Number in full:||1462|
|Average length of the domain:||439.80 aa|
|Average identity of full alignment:||25 %|
|Average coverage of the sequence by the domain:||82.67 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null --hand HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||15|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the OATP domain has been found. There are 1 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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