Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.11 (AMPK)
 12,425 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Trehalase activity in Rhodotorula rubra was found to be bound to the particulate fraction of a cell-free extract in contrast with the soluble trehalase activity of Saccharomyces cerevisiae. The enzyme was strongly repressed by glucose and derepressed during growth on maltose, trehalose and glycerol. This increase in activity was due to a "de novo" synthesis as seen by inhibition with cycloheximide, a mechanism not described for Saccharomyces cerevisiae. Catabolite inactivation by addition of glucose was also demonstrated. This particulate enzyme does not respond to activation by the cAMP-dependent protein kinase.
 ...
PMID:Characterization of trehalase in Rhodotorula rubra. 148 5

Cryptic trehalase from Saccharomyces cerevisiae was purified about 3000-fold. The recovery of 970% of the original "activity" indicated the removal of an inhibitor of the enzyme. Active trehalase, obtained through phosphorylation of cryptic trehalase by cAMP-dependent protein kinase, was isolated by chromatography on DEAE-cellulose. A major phosphorylated protein, with an apparent Mr of 86,000, was detected after SDS-polyacrylamide gel electrophoresis. This protein band correlated exactly with the elution profile of trehalase activity and 32Pi incorporation into the enzyme on DEAE-cellulose chromatography. Partially purified active trehalase showed absolute specificity towards trehalose with an apparent Km of 4.79 X 10(-3) M. Both forms of the enzyme showed an apparent molecular weight of 160,000, by gel filtration. Centrifugation on a glycerol density gradient indicated multiple forms of trehalase-c, with Mr of 320,000, 160,000, and 80,000. After activation of each of these forms by protein kinase, a single form of trehalase-a was observed, with a Mr of 160,000. Trehalase-c appears to be a totally inactive form of the enzyme. The only mechanism of activation seems to be phosphorylation by cAMP-dependent protein kinase. When the protein kinase concentration was varied, at a fixed trehalase-c concentration, a sigmoidal activation plot was obtained. This result suggests the occurrence of multiple forms of cryptic trehalase.
 ...
PMID:Partial purification and characterization of the interconvertible forms of trehalase from Saccharomyces cerevisiae. 302 71

Mutation at the GLC1 locus in Saccharomyces cerevisiae resulted in simultaneous deficiencies in glycogen and trehalose accumulation. Extracts of yeast cells containing the glc1 mutation exhibited an abnormally high trehalase activity. This elevated activity was associated with a defective cyclic AMP (cAMP)-dependent monocyclic cascade which, in normal cells, regulates trehalase activity by means of protein phosphorylation and dephosphorylation. Trehalase in extracts of normal cells was largely in a cryptic form which could be activated in vitro by ATP . Mg in the presence of cAMP. Normal extracts also exhibited a correlated cAMP-dependent protein kinase which catalyzed incorporation of label from [gamma-32P]ATP into protamine. In contrast, cAMP had little or no additional activating effect on trehalase or on protamine phosphorylation in extracts of glc1 cells. Similar, unregulated activation of cryptic trehalase was also found in glycogen-deficient strains bearing a second, independently isolated mutant allele, glc1-2. Since trehalase activity was not directly affected by cAMP, the results indicate that the glc1 mutation results in an abnormally active protein kinase which has lost its normal dependence on cAMP. Trehalase in extracts of either normal or mutant cells underwent conversion to a cryptic form in an Mg2+-dependent, fluoride-sensitive reaction. Rates of this reversible reduction of activity were similar in extracts of mutant and normal cells. This same, unregulated protein kinase would act on glycogen synthase, maintaining it in the phosphorylated low-activity D-form. The glc1 mutants provide a novel model system for investigating the in vivo metabolic functions of a specific, cAMP-dependent protein kinase.
 ...
PMID:Regulation of yeast trehalase by a monocyclic, cyclic AMP-dependent phosphorylation-dephosphorylation cascade system. 629 49

Trehalase activity is markedly enhanced upon addition of glucose and a nitrogen source to cells of the fission yeast Schizosaccharomyces pombe. This increase corresponds to a post-translational activation of the enzyme, which is controlled by cAMP-dependent and cAMP-independent pathways. Recent work has shown that overexpression of SCK1 in Schiz. pombe is able to suppress mutations that result in reduced Pka1 (cAMP-dependent protein kinase A activity, suggesting that Sck1 (suppressor of loss of cAMP-dependent protein kinase) might be a functional analogue of Pka1 in the fission yeast. Here, an analysis of the possible role of Sck1 in the activation of trehalase triggered by glucose and a nitrogen source is reported in cells that were deficient in either Pka1, Sck1 or both protein kinases. The results showed that, except in repressed cells, Sck1 probably mediates a cAMP-independent activation of trehalase following the signal(s) triggered by glucose and the nitrogen source. The absence of functional Sck1 in depressed cells renders trehalase insensitive to activation by glucose and the nitrogen source even in the presence of Pka1, indicating that the Sck1-dependent, cAMP-independent pathway is the main signalling pathway controlling trehalase activation under derepression conditions. It is proposed that, during the activation of trehalase induced by glucose or a nitrogen source, the cAMP-Pka1 activation pathway previously characterized is to some extent parallel to this newly described one which includes Sck1 as phosphorylating enzyme. Neither of these two pathways, however, plays a key role in the heat-induced increase in trehalase activity.
 ...
PMID:Protein kinase Sck1 is involved in trehalase activation by glucose and nitrogen source in the fission yeast Schizosaccharomyces pombe. 924 26