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'''Transporter Classification database''' (or '''TCDB''') is an [[International Union of Biochemistry and Molecular Biology]] (IUBMB) approved classification system for membrane [[transport protein]]s including [[ion channel]]s.<ref name="pmid19022853">{{cite journal |author=Saier MH, Yen MR, Noto K, Tamang DG, Elkan C |title=The Transporter Classification Database: recent advances |journal=Nucleic Acids Res. |volume=37 |issue=Database issue |pages=D274–8 |year=2009 |month=January |pmid=19022853 |pmc=2686586 |doi=10.1093/nar/gkn862 |url=http://nar.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=19022853}}</ref> This classification system was designed to be analogous to the [[EC number]] system for classifying [[enzymes]], but it also uses phylogenetic information.
==Classification==
The upper level of classification and a few examples of proteins with known 3D structure:
'''===1. Channels/Pores'''===
**[[Voltage-gated ion channel]] like, including [[potassium channel]]s KcsA and KvAP, and [[inward-rectifier potassium ion channel]] Kirbac [http://opm.phar.umich.edu/families.php?superfamily=8]
**[[Large-conductance mechanosensitive channel, MscL]] [http://opm.phar.umich.edu/families.php?superfamily=12]
**[[Mechanosensitive ion channel|Small-conductance mechanosensitive ion channel (MscS)]] [http://opm.phar.umich.edu/families.php?superfamily=11]
**[[Magnesium transporters|CorA metal ion transporters]] [http://opm.phar.umich.edu/families.php?superfamily=72]
**[[Ligand-gated ion channel]] of [[neurotransmitter]] receptors ([[acetylcholine receptor]]) [http://opm.phar.umich.edu/families.php?superfamily=14]
**[[Aquaporin]]s [http://opm.phar.umich.edu/families.php?superfamily=7]
**[[Chloride channel]]s [http://opm.phar.umich.edu/families.php?superfamily=10]
**Outer membrane auxiliary proteins (polysaccharide transporter) [http://opm.phar.umich.edu/families.php?superfamily=188]
**[[Porin (protein)|Porins]] and some other [[beta barrel]] proteins of [[outer membrane]]s
'''===2. Electrochemical Potential-driven transporters'''===
**[[Mitochondrial]] [[carrier protein]]s [http://opm.phar.umich.edu/families.php?superfamily=21]
**Major Facilitator Superfamily (Glycerol-3-phosphate transporter, Lactose [[permease]], and Multidrug transporter EmrD) [http://opm.phar.umich.edu/families.php?superfamily=15]
**Resistance-nodulation-cell division (multidrug [[efflux]] transporter AcrB, see [[multidrug resistance]])[http://opm.phar.umich.edu/families.php?superfamily=16]
**Dicarboxylate/amino acid:cation symporter (proton glutamate symporter) [http://opm.phar.umich.edu/families.php?superfamily=20]
**Monovalent cation/proton antiporter (Sodium/proton antiporter 1 NhaA) [http://opm.phar.umich.edu/families.php?superfamily=66]
**[[Neurotransmitter]] sodium symporter [http://opm.phar.umich.edu/families.php?superfamily=67]
**Ammonia transporters [http://opm.phar.umich.edu/families.php?superfamily=13]
**Drug/Metabolite Transporter (small multidrug resistance transporter EmrE - the structures are retracted as erroneous) [http://opm.phar.umich.edu/families.php?superfamily=77]
'''===3. Primary Active Transporters'''===
*Light absorption-driven transporters:
**[[Bacteriorhodopsin]]-like proteins including [[rhodopsin]] (see also [[opsin]])[http://opm.phar.umich.edu/families.php?superfamily=6]
**General [[secretory pathway]] (Sec) [[translocon]] (preprotein translocase SecY) [http://opm.phar.umich.edu/families.php?superfamily=19]
'''===4. Group Translocators'''===
'''===5. Transport Electron Carriers'''===
**Disulfide bond formation protein B (DsbB) [http://opm.phar.umich.edu/protein.php?search=2hi7]
'''8. Accessory Factors Involved in Transport''' ▼
===6. Unused===
'''9. Incompletely Characterized Transport Systems''' ▼Reserved for future expansion
===7. Unused===
Reserved for future expansion
▲'''===8. Accessory Factors Involved in Transport '''===
▲'''===9. Incompletely Characterized Transport Systems '''===
==Examples==
==See also==
* [[List of proteins]]
==References==
{{reflist}}
==External links==
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