Citrate/sodium symporter

UniProtKB accession:  P31602

Grouped By:  Matching UniProtKB accession

UniProtKB description:  Secondary active transporter that catalyzes the uptake of citrate across the membrane with the concomitant uptake of sodium (PubMed:10985744, PubMed:12911322, PubMed:1577734, PubMed:1629151, PubMed:8125105, PubMed:8547237). There are conflicting data regarding exact substrate stoichiometry: the sodium/citrate stoichiometry was predicted to be 1, but the latest studies suggest that CitS transports citrate in symport with 2 sodium ions (PubMed:12911322, PubMed:1629151, PubMed:8125105, PubMed:8547237). Transports citrate as a divalent citrate anion, H-citrate(2-) (PubMed:10985744, PubMed:1629151, PubMed:8547237). Shows narrow substrate specificity and is very specific, transporting only citrate and to a low extent citromalate (PubMed:9218448). Symport of Na(+) is absolutely required in the range pH 5-7 because no uptake can be detected in the absence of Na(+) (PubMed:12911322, PubMed:8125105). Lithium can replace Na(+) in the symport reaction but it takes about a 200-fold higher concentration of Li(+) over Na(+) to achieve the same rate of uptake (PubMed:8125105).