Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Down-regulation ("curb") of hexose transport in Chinese hamster lung fibroblasts has been studied in a metabolic mutant highly defective in phosphoglucose isomerase (PGI; glucosephosphate isomerase; D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9). In the parental strain (PGI+) glucose as well as glucosamine and mannose were able to elicit a curb of the hexose transport system. In the PGI mutant, only glucose was able to mediate a transport curb. The inability of glucosamine and mannose to promote a transport curb in the PGI strain must be ascribed to the fact that the 6-esters of these aldohexoses are converted by their own specific deaminase and isomerase to fructose 6-phosphate, which initiates the pyruvate-tricarboxylate energy-yielding pathway but cannot be converted to glucose 6-phosphate in the mutant. The latter ester can be metabolized, but its metabolism in the mutant is confined to the pentose shunt. It is shown that inhibitors such as 2,4-dinitrophenol and malonate exert only slight inhibition of the pentose shunt yet release the glucose-mediated curb elicited by glucose and glucosamine in the parental PGI+ strain and also the glucose transport curb persisting in the PGI mutant.
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PMID:Down-regulation of the hexose transport system: metabolic basis studied with a fibroblast mutant lacking phosphoglucose isomerase. 695 19

Functional and structural properties of several truncated or mutated variants of Candida albicans Gfa1p (glucosamine-6-phosphate synthase) were compared with those of the wild-type enzyme. Fragments encompassing residues 1-345 and 346-712 of Gfa1p, expressed heterogeneously in bacterial host as His6 fusions, were identified as the functional GAH (glutamine amidehydrolysing) and ISOM (hexose phosphate-isomerizing) domains respectively. It was found that the native GAH domain is monomeric, whereas the native ISOM domain forms tetramers, as does the whole enzyme. Spectrofluorimetric and kinetic studies of the isolated domains, the Delta218-283Gfa1p mutein and the wild-type enzyme revealed that the binding site for the feedback inhibitor, uridine 5'-diphospho-N-acetyl-D-glucosamine, is located in the ISOM domain. Inhibitor binding affects amidohydrolysing activity of the GAH domain and, as a consequence, the GlcN-6-P (D-glucosamine-6-phosphate)-synthetic activity of the whole enzyme. The fragment containing residues 218-283 is neither involved in ligand binding nor in protein oligomerization. Comparison of the catalytic activities of Gfa1p(V711F), Delta709-712Gfa1p, Gfa1p(W97F) and Gfa1p(W97G) with those of the native Gfa1p and the isolated domains provided evidence for an intramolecular channel connecting the GAH and ISOM domains of Gfa1p. The channel becomes leaky upon deletion of amino acids 709-712 and in the W97F and W97G mutants. The Trp97 residue was found to function as a molecular gate, opening and closing the channel. The W97G and V711F mutations resulted in an almost complete elimination of the GlcN-6-P-synthetic activity, with the retention of the amidohydrolase and sugar phosphate-isomerizing activities.
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PMID:Functional domains and interdomain communication in Candida albicans glucosamine-6-phosphate synthase. 1730 46

Cultural practices for canopy management in grapevines rely on intensive manipulation of shoot architecture to maintain canopy light levels. In contrast to common model plant systems used to study regulation of branch outgrowth, the grapevine has a more complex architecture. The node contains first, second and third order axillary meristems. The prompt bud (N+1) develops into a summer lateral and a latent compound bud develops in the basal node of the summer lateral (N+2, N+3(1,2)). The outgrowth potential of latent buds was determined using common canopy management treatments (shoot tip decapitation and removal of summer laterals and leaves) and monitoring the rate of latent bud outgrowth. Two shoot node regions (apical and basal) with differential outgrowth potential were characterized and it was noted that the shoot tip, summer laterals and leaves in addition to node position contributed to the inhibition of latent bud outgrowth. To advance the understanding of the molecular regulation of bud outgrowth and paradormancy in the complex shoot architecture of grapevines, the expression of auxin and cytokinin genes involved in branching (amidase (VrAMI1), PINFORMED-3 (VrPIN3) and isopentenyl transferase (VrIPT)) were monitored in shoot tips and differentially aged buds of Vitis riparia grapevine shoots. In addition, Histone 3 (VrH3) and a hexose transporter (VrHT1) expression were monitored as a measure of tissue activity. The expression of VrAMI1 and VrPIN3 remained constant in actively growing shoot tips and decreased significantly with increasing bud maturation in paradormant buds. VrHT1 expression was greater in buds than in any other plant tissue tested. VrHT1 may have the potential to be used as an indicator of paradormancy status in grapevines. These characterizations in the complex architecture of the grapevine provide an excellent model system for molecular analysis of bud outgrowth and shoot architecture development.
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PMID:Auxin and cytokinin related gene expression during active shoot growth and latent bud paradormancy in Vitis riparia grapevine. 2232 93