Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.1.14 (SPS)
 813 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report an Mg2+-dependent interaction between spinach leaf sucrose-phosphate synthase (SPS) and endogenous 14-3-3 proteins, as evidenced by co-elution during gel filtration and co-immunoprecipitation. The content of 14-3-3s associated with an SPS immunoprecipitate was inversely related to activity, and was specifically reduced when tissue was pretreated with 5-aminoimidazole-4-carboxamide riboside, suggesting metabolite control in vivo. A synthetic phosphopeptide based on Ser-229 was shown by surface plasmon resonance to bind a recombinant plant 14-3-3, and addition of the phosphorylated SPS-229 peptide was found to stimulate the SPS activity of an SPS:14-3-3 complex. Taken together, the results suggest a regulatory interaction of 14-3-3 proteins with Ser-229 of SPS.
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PMID:Site-specific regulatory interaction between spinach leaf sucrose-phosphate synthase and 14-3-3 proteins. 975 69

Far-Western overlays of soluble extracts of cauliflower revealed many proteins that bound to digoxygenin (DIG)-labelled 14-3-3 proteins. Binding to DIG-14-3-3s was prevented by prior dephosphorylation of the extract proteins or by competition with 14-3-3-binding phosphopeptides, indicating that the 14-3-3 proteins bind to phosphorylated sites. The proteins that bound to the DIG-14-3-3s were also immunoprecipitated from extracts with anti-14-3-3 antibodies, demonstrating that they were bound to endogenous plant 14-3-3 proteins. 14-3-3-binding proteins were purified from cauliflower extracts, in sufficient quantity for amino acid sequence analysis, by affinity chromatography on immobilised 14-3-3 proteins and specific elution with a 14-3-3-binding phosphopeptide. Purified 14-3-3-binding proteins included sucrose-phosphate synthase, trehalose-6-phosphate synthase, glutamine synthetases, a protein (LIM17) that has been implicated in early floral development, an approximately 20 kDa protein whose mRNA is induced by NaCl, and a calcium-dependent protein kinase that was capable of phosphorylating and rendering nitrate reductase (NR) sensitive to inhibition by 14-3-3 proteins. In contrast to the phosphorylated NR-14-3-3 complex which is activated by dissociation with 14-3-3-binding phosphopeptides, the total sugar-phosphate synthase activity in plant extracts was inhibited by up to 40% by a 14-3-3-binding phosphopeptide and the phosphopeptide-inhibited activity was reactivated by adding excess 14-3-3 proteins. Thus, 14-3-3 proteins are implicated in regulating several aspects of primary N and C metabolism. The procedures described here will be valuable for determining how the phosphorylation and 14-3-3-binding status of defined target proteins change in response to extracellular stimuli.
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PMID:Phosphorylation-dependent interactions between enzymes of plant metabolism and 14-3-3 proteins. 1034 39

Despite 14-3-3 proteins being implicated in the control of the eukaryotic cell cycle, metabolism, cell signalling and survival, little is known about the global regulation or functions of the phosphorylation-dependent binding of 14-3-3s to diverse target proteins. We identified Arabidopsis cytosolic proteins that bound 14-3-3s in competition with a 14-3-3-binding phosphopeptide, including nitrate reductase, glyceraldehyde- 3-phosphate dehydrogenase, a calcium-dependent protein kinase, sucrose-phosphate synthase (SPS) and glutamyl-tRNA synthetase. Remarkably, in cells starved of sugars or fed with non-metabolizable glucose analogues, all 14-3-3 binding was lost and the target proteins were selectively cleaved into proteolytic fragments. 14-3-3 binding reappeared after several hours of re-feeding with sugars. Starvation-induced degradation was blocked by 5-amino imidazole-4-carboxamide riboside (which is converted to an AMP-mimetic) or the protease inhibitor MG132 (Cbz-leu-leu-leucinal). Extracts of sugar-starved (but not sugar-fed) Arabidopsis cells contained an ATP-independent, MG132-sensitive, neutral protease that cleaved Arabidopsis SPS, and the mammalian 14-3-3-regulated transcription factor, FKHR. Cleavage of SPS and phosphorylated FKHR in vitro was blocked by binding to 14-3-3s. The finding that 14-3-3s participate in a nutrient-sensing pathway controlling cleavage of many targets may underlie the effects of these proteins on plant development.
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PMID:14-3-3s regulate global cleavage of their diverse binding partners in sugar-starved Arabidopsis cells. 1085 32

Protein phosphorylation is key to the regulation of many proteins. Altered protein activity often requires the interaction of the phosphorylated protein with a class of "adapters" known as 14-3-3 proteins. This review will cover aspects of 14-3-3 interaction with key proteins of carbon and nitrogen metabolism such as nitrate reductase, glutamine synthetase and sucrose-phosphate synthase. It will also address 14-3-3 involvement in signal transduction pathways with emphasis on the regulation of plant metabolism. To date, 14-3-3 proteins have been identified and studied in many diverse systems, yielding a plethora of data, requiring careful analysis and interpretation. Problems such as these are not uncommon when dealing with multigene families. The number of isoforms makes the question of redundancy versus specificity of 14-3-3 proteins a crucial one. This issue is discussed in relation to structure, function and expression of 14-3-3 proteins.
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PMID:Function and specificity of 14-3-3 proteins in the regulation of carbohydrate and nitrogen metabolism. 1250 70

Brassinosteroids (BRs), a new class of steroid hormones, are involved in the regulation of plant cell elongation and seed germination. Nevertheless, the molecular mechanism of the effect of BRs on tuber sprouting remains largely unknown. In this study, quantitative phosphoproteomics was employed to investigate the protein phosphorylation changes in sprouting induced by BRs. Our results showed that BRs accelerated the conversion of starch into soluble sugar in tubers. A functional enrichment cluster analysis suggested that the "amino acid metabolism pathway" was upregulated and that "plant hormone signal transduction and protein export" were downregulated. BR treatment also changed the phosphorylation of proteins involved in the BR, ABA, starch and sugar signal transduction pathways, such as serine/threonine-protein kinase (BSK), 14-3-3, alpha-glucan water dikinase (GWD), sucrose-phosphate synthase (SPS), sucrose synthase (SS) and alkaline/neutral invertase (A/N-INV). These results shed more light on the pattern of protein phosphorylation in BR promoting potato sprouting.
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PMID:Quantitative phosphoproteomics analysis reveals that protein modification and sugar metabolism contribute to sprouting in potato after BR treatment. 3238 93