| 词条 | NiCoT family |
| 释义 |
Proteins currently known to belong to the Ni2+-Co2+ Transporter (NiCoT) family (TC# 2.A.52) can be found in organisms ranging from Gram-negative and Gram-positive bacteria to archaea and some eukaryotes. Members of this family catalyze uptake of Ni2+ and/or Co2+ in a proton motive force-dependent process.[1] StructureThese proteins range in size from about 300 to 400 amino acyl residues and possess 6, 7, or 8 transmembrane segments (TMSs), thought to result from an intragenic 4 TMS duplication, followed by a deletion of one or two TMSs in the cases of the 7 or 6 TMS proteins. Topological analyses with the HoxN Ni2+ transporter of Ralstonia eutropha (Alcaligenes eutrophus) suggest that it possesses 8 TMSs with its N- and C-termini in the cytoplasm. The Co2+ (Ni2+) transporter of Rhodococcus rhodochrous, NhlF, exhibits eight putative TMSs, and eight apparent TMSs are revealed by hydropathy analyses of multiple alignments of family protein sequences. An HX4DH motif in helix 2 of the HoxN protein has been implicated in Ni2+ binding, and both helix 1 and helix 2, which interact spatially, form the selectivity filter.[2] In the Helicobacter pylori NixA homologue, several conserved motifs have been shown to be important for Ni2+ binding and transport.[1][3] At least one crystal structure is known, determined by Yu et al.,[4] available at {{PDB|4M58}}. ReactionThe overall reaction catalyzed by the proteins of the NiCoT family is:[1] [Ni2+ and/or Co2+] (out) → [Ni2+ and/or Co2+] (in). ProteinsSeveral characterized proteins belong to the Ni2+-Co2+ Transporter (NiCoT) Family (TC# 2.A.43). A complete list of these proteins along with their transporter classification identification numbers (TCID), domain, kingdom/phylum, and some examples can be found in the Transporter Classification Database. References1. ^1 2 {{cite web|last1=Saier|first1=Milton|title=Transporter Classification Database: 2.A.52 The Ni2+-Co2+ Transporter (NiCoT) Family|url=http://www.tcdb.org/search/result.php?tc=2.a.52|website=tcdb.org|accessdate=4 January 2016}} 2. ^{{cite journal|last1=Degen|first1=O|last2=Eitinger|first2=T|title=Substrate specificity of nickel/cobalt permeases: insights from mutants altered in transmembrane domains I and II.|journal=J. Bacteriol.|date=July 2002|volume=184|issue=13|pages=3569–77|pmc=135128|pmid=12057951|doi=10.1128/jb.184.13.3569-3577.2002}} 3. ^{{cite journal|last1=Wolfram|first1=L|last2=Bauerfeind|first2=P|title=Conserved low-affinity nickel-binding amino acids are essential for the function of the nickel permease NixA of Helicobacter pylori |journal=J. Bacteriol.|date=March 2002|volume=184|issue=5|pages=1438–43|doi=10.1128/JB.184.5.1438-1443.2002 |pmid=11844775|pmc=134868}} 4. ^{{cite journal|last1=Yu|first1=Y|last2=Zhou|first2=M|last3=Kirsch|first3=F|last4=Xu|first4=C|last5=Zhang|first5=L|last6=Wang|first6=Y|last7=Jiang|first7=Z|last8=Wang|first8=N|last9=Li|first9=J|last10=Eitinger|first10=T|last11=Yang|first11=M|title=Planar substrate-binding site dictates the specificity of ECF-type nickel/cobalt transporters|journal=Cell Research|date=December 24, 2013|volume=24|issue=3|pages=267–277|doi=10.1038/cr.2013.172|pmid=24366337|pmc=3945884}} Further reading{{refbegin|30em}}
6 : Membrane proteins|Enzymes of known structure|Solute carrier family|Transmembrane proteins|Transmembrane transporters|Transport proteins |
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