Phosphate carrier

Tsuji, A. and I. Tamai. Na+ and pH dependent transport of foscamet via the phosphate carrier system across intestinal brush-border membrane. Biochem. Pharmacol 1989, 38, 1019— 1022. 

Hall, J. A., Fann, M. C. and Maloney, P. C. (1999). Altered substrate selectivity in a mutant of an intrahelical salt bridge in UhpT, the sugar phosphate carrier of Escherichia coli, J. Biol. Chem., 274, 6148-6153. 

Zara V, Palmieri F, Mahlke K, Pfanner N (1992) The cleavable presequence is not essential for import and assembly of the phosphate carrier of mammalian mitochondria but enhances the specificity and efficiency of import. J Biol Chem 267 12077-12081... 

S phosphoenolpyruvate -I- fructose <8> (<8> no evidence for requirement of a phosphate carrier such as HPr (i.e. histidine-containing protein) for phosphorylation of fructose [12]) [12]... 

The odontoblasts secrete an extracellular matrix that is rich in collagen I and which also contains all of the other major bone proteins as well as a dentin sialoprotein and poorly characterized phosphate carriers, the phosphophoryns. 

Phosphonoformic acid (Foscarnet), an antiviral drug, which consists of carboxylic acid and phosphate linked together, was shown to be absorbed in the small intestine by the phosphate carrier-mediated mechanism [154], The transport of folic acid was investigated in biopsy specimens of intestinal mucosa from healthy volunteers. A pH-dependent, active transport of folic acid was found in the proximal small intestine, whereas in the mucosa of the colon, folic acid uptake was driven by a facilitated diffusion, mediated by a low-affinity carrier [155]. The existence of folate receptors in the human colonic mucosa is logical due to the large amounts of folic acid produced by the colonic flora [145],... 

Fig. 4. Synthesis of N-linked oligosaccharides on a dolichol phosphate carrier in the RER membrane.

P, Sperl W. Mitochondrial phosphate-carrier deficiency a novel 36. 

Fig. 2.2. The chemiosmotic proton circuit, a, during the synthesis of matrix ATP (State 3) b, during the synthesis of extra-mitochondrial ATP (State 3) c, during State 4 respiration d, in the presence of proton translocator. R, respiratory chain A, ATP synthase P, phosphate carrier U, uncoupler. The respiratory chain is simplified to a single proton pump.

However, since the proportion of most metabohtes present as free acid at pH 7 is low, it is likely that the carriers have separate binding sites for protons and anions. The relationships between proton concentrations, substrate concentrations and rates of transport have been examined in order to gain insight into the molecular mechanisms of transport for the glutamate, pyruvate and phosphate carriers. 

A particularly reactive sulfhydryl group (or groups) on the phosphate transporter react with relatively low concentrations of maleimide derivatives and organic mercurials to inhibit the function of the transporter [17]. This sulfhydryl group is probably near, or a part of, the substrate binding site because phosphate protects the carrier activity from inhibition by A-ethylmaleimide. Fonyo has written a comprehensive review on the subject of sulfhydryl sensitivity of the phosphate carrier and its implications concerning the mechanism of transport [192]. 

ATP-ADP translocase is but one of many mitochondrial transporters for ions and charged metabolites (Figure 18.39). The phosphate carrier, which works in concert with AT F-ADP translocase mediates the elec-troneutral exchange of H7P04 for OH . The combined action of these two transporters leads to the exchange of cytoplasmic ADP and Pj for ma trix ATP at the cost of the influx of one H" " (owing to the transport of one OH out of the matrix). These two transporters, which provide ATP synthase with its substrates, are associated with the synthase to form a large complex called the ATP synthasome. 

Non-sulfur, purple, photosynthetic bacteria, Rho do spirillum rub-rum and Rhodopseudomonas spheroides172 also possess a PEP-de-pendent D-fructose phosphotransferase. Two protein fractions are required for D-fructose phosphorylation. In contrast to PEP-depend-ent, phosphotransferase systems isolated from other bacteria, the aforementioned two organisms have one active protein fraction tightly associated with the membrane fraction, while another in the crude extract is solubilized by extraction with water, and has a molecular weight of about 200,000. There is no evidence for the presence of a phosphate-carrier protein of low molecular weight like HPr.171,173 The... 

Briand, Y., Debise, R., Durand, R. Biochimie 57 (6-7), 787 (1975). Effect of phosphate and ionophores on (14C)-NEM incorporation in mitochondrial membranes and relationships with phosphate carrier system... 

Pyridoxine (65) Pyridoxal phosphate Pyridoxamine phosphate Carriers of amino and carboxyl groups... 

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