The Plastidic Pentose Phosphate Translocator Represents a Link between the Cytosolic and the Plastidic Pentose Phosphate Pathways in Plants

摘要: Plastids are the site of reductive and oxidative pentose phosphate pathways, which both generate phosphates as intermediates. A plastidic transporter from Arabidopsis has been identified that is able to transport, in exchange with inorganic or triose phosphates, xylulose 5-phosphate (Xul-5-P) and, a lesser extent, also ribulose 5-phosphate, but does not accept ribose hexose substrates. Under physiological conditions, Xul-5-P would be preferred substrate. Therefore, translocator was named Xul-5-P/phosphate (XPT). The XPT shares only approximately 35% 40% sequence identity members phosphoenolpyruvate/phosphate classes, higher 50% glucose 6-phosphate/phosphate translocators. it represents fourth group Database analysis revealed plant cells contain, addition enzymes branch pathway, isomerase epimerase cytosol plastids, whereas transketolase transaldolase converting produced probably solely confined plastids. It assumed function provide pathways cytosolic carbon skeletons form Xul-5-P, especially under conditions high demand for intermediates cycles.