Marqueur métabolique : Citrate transporter CitP (CITP)
Secondary transporter involved in citrate metabolism (PubMed:7592702, PubMed:8636016, PubMed:9572922). During cometabolism of citrate and glucose, catalyzes the uptake of divalent citrate into the cell coupled to the exit of monovalent lactate, a product of citrate fermentation during citrate-glucose cometabolism (precursor/product exchange) (PubMed:7592702, PubMed:8636016, PubMed:9572922). The citrate/lactate exchange is electrogenic and results in the generation of a membrane potential (PubMed:7592702, PubMed:8636016, PubMed:9572922). In the absence of glucose, i.e. when no lactate is produced, CitP catalyzes the proton-dependent transport of citrate and malate (PubMed:7592702). Transports the divalent form of citrate and malate with the concomitant uptake of one proton, therefore translocating a single unit of negative charge across the membrane (PubMed:7592702). In vitro, transports a range of substrates that contain the 2-hydroxycarboxylate motif, HO-CR(2)-COO(-), with a preference for malate, citrate and monovalent 2-hydroxyisobutyrate (PubMed:10441129, PubMed:9218448). Modification of the OH or the COO(-) groups of the 2-hydroxycarboxylate motif drastically reduces the affinity of the transporter for the substrates, indicating their relevance in substrate recognition (PubMed:10441129). Significant activity is also observed with some 2-oxocarboxylates and a 3-hydroxycarboxylate (PubMed:9218448)