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2.A.88.3.2
Thiamin transporter, ThiT (Thiamin ECF transporter S component) (Rodionov et al. 2002; Rodionov et al., 2009). High affinity thiamin transporter ThiT (Ka=120 pM). Other substrates include TPP, TMP and pyrithiamin with nM binding constants at 1:1 stoichiometry (protein:ligand). Binding depends on a tryptophan-rich loop between TMSs 5 and 6 (Erkens and Slotboom, 2010). Erkens et al. (2011) presented the crystal structure of the thiamine-specific S-component of the ECF-type ABC transporter, ThiT from Lactococcus lactis at 2.0 Å. Extensive protein-substrate interactions explain its high binding affinity for thiamine (Kd ~ 10-10 M). ThiT has a fold similar to that of the riboflavin-specific S-component RibU, with which it shares only 14% sequence identity. Two alanines in a conserved motif (AxxxA) located on the membrane-embedded surface of the S-components mediate the interaction with the energizing module. A general transport mechanism for ECF transporters has been proposed (Erkens et al., 2011).  Substrate binding induces conformational changes in ThiT (Majsnerowska et al. 2013).

Accession Number:A2RI47
Protein Name:Putative membrane protein
Length:182
Molecular Weight:19909.00
Species:lactococcus lactis subsp. cremoris (strain mg1363) [416870]
Number of TMSs:4
Location1 / Topology2 / Orientation3: Membrane1 / Multi-pass membrane protein2
Substrate thiamin, thiamin pyrophosphate, thiamin monophosphate, Pyrithiamin

Cross database links:

eggNOG: COG3859
HEGENOM: HBG421996
RefSeq: YP_001031688.1   
Entrez Gene ID: 4796873   
Pfam: PF09515   
KEGG: llm:llmg_0334   

References (1)

[1] “The complete genome sequence of the lactic acid bacterial paradigm Lactococcus lactis subsp. cremoris MG1363.”  Wegmann U.et.al.   17307855
Structure:
4POP   4POV   3rlb   4mes     

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MSNSKFNVRL LTEIAFMAAL AFIISLIPNT VYGWIIVEIA CIPILLLSLR RGLTAGLVGG 
61:	LIWGILSMIT GHAYILSLSQ AFLEYLVAPV SLGIAGLFRQ KTAPLKLAPV LLGTFVAVLL 
121:	KYFFHFIAGI IFWSQYAWKG WGAVAYSLAV NGISGILTAI AAFVILIIFV KKFPKLFIHS 
181:	NY