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2.A.15.2.1
Carnitine:γ-butyrobetaine antiporter.  The x-ray structure is known at 3.5 Å resolution (Schulze et al., 2010).  The structure reveals a homotrimer where each protomer has 12 TMSs with 4 L-carnitine molecules outlining the pathway.  There is a central binding site and another in the intracellular vestibule (Tang et al. 2010).

Accession Number:P31553
Protein Name:CaiT aka B0040
Length:504
Molecular Weight:56587.00
Species:Escherichia coli [83333]
Number of TMSs:12
Location1 / Topology2 / Orientation3: Cell inner membrane1 / Multi-pass membrane protein2
Substrate Carnitine, Gamma-butyrobetaine

Cross database links:

Genevestigator: P31553
EchoBASE: EB1522
EcoGene: EG11561
eggNOG: COG1292
HEGENOM: HBG682943
DIP: DIP-9247N
RefSeq: AP_000704.1    NP_414582.1   
Entrez Gene ID: 944765   
Pfam: PF02028   
BioCyc: EcoCyc:CAIT-MONOMER    ECOL168927:B0040-MONOMER   
KEGG: ecj:JW0039    eco:b0040   

Gene Ontology

GO:0016021 C:integral to membrane
GO:0005886 C:plasma membrane
GO:0015297 F:antiporter activity
GO:0006810 P:transport

References (7)

[1] “Molecular characterization of the cai operon necessary for carnitine metabolism in Escherichia coli.”  Eichler K.et.al.   7815937
[2] “Systematic sequencing of the Escherichia coli genome: analysis of the 0-2.4 min region.”  Yura T.et.al.   1630901
[3] “The complete genome sequence of Escherichia coli K-12.”  Blattner F.R.et.al.   9278503
[4] “Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110.”  Hayashi K.et.al.   16738553
[5] “CaiT of Escherichia coli, a new transporter catalyzing L-carnitine/gamma-butyrobetaine exchange.”  Jung H.et.al.   12163501
[6] “Rates of DNA sequence evolution in experimental populations of Escherichia coli during 20,000 generations.”  Lenski R.E.et.al.   12664169
[7] “Global topology analysis of the Escherichia coli inner membrane proteome.”  Daley D.O.et.al.   15919996
Structure:
2WSX   3HFX     

External Searches:

  • Search: DB with
  • BLAST ExPASy (Swiss Institute of Bioinformatics (SIB) BLAST)
  • CDD Search (Conserved Domain Database)
  • Search COGs (Clusters of Orthologous Groups of proteins)
  • 2° Structure (Network Protein Sequence Analysis)

Analyze:

Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MKNEKRKTGI EPKVFFPPLI IVGILCWLTV RDLDAANVVI NAVFSYVTNV WGWAFEWYMV 
61:	VMLFGWFWLV FGPYAKKRLG NEPPEFSTAS WIFMMFASCT SAAVLFWGSI EIYYYISTPP 
121:	FGLEPNSTGA KELGLAYSLF HWGPLPWATY SFLSVAFAYF FFVRKMEVIR PSSTLVPLVG 
181:	EKHAKGLFGT IVDNFYLVAL IFAMGTSLGL ATPLVTECMQ WLFGIPHTLQ LDAIIITCWI 
241:	ILNAICVACG LQKGVRIASD VRSYLSFLML GWVFIVSGAS FIMNYFTDSV GMLLMYLPRM 
301:	LFYTDPIAKG GFPQGWTVFY WAWWVIYAIQ MSIFLARISR GRTVRELCFG MVLGLTASTW 
361:	ILWTVLGSNT LLLIDKNIIN IPNLIEQYGV ARAIIETWAA LPLSTATMWG FFILCFIATV 
421:	TLVNACSYTL AMSTCREVRD GEEPPLLVRI GWSILVGIIG IVLLALGGLK PIQTAIIAGG 
481:	CPLFFVNIMV TLSFIKDAKQ NWKD