Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PHOSPHORYLASE KINASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,333 records · Page 74Linked to original sources
PubMedDate not supplied

Protein kinase C activation induces conductance changes in Hermissenda photoreceptors like those seen in associative learning.

Phosphorylation of ion channels has been suggested as one molecular mechanism responsible for learning-produced long-term changes in neuronal excitability. Persistent training-produced changes in two distinct K+ currents (IA (ref. 2), IK-Ca (refs 3,4)) and a voltage-dependent calcium current (ICa; refs 3,4) have previously been shown to occur in type B photoreceptors of Hermissenda, as a result of associative learning. But the identity of the phosphorylation pathway(s) responsible for these changes has not as yet been determined. Injections of cyclic AMP-dependent protein kinase reduce a K+ current (IK) in B cells which is different from those changed by training, but fails to reduce IA and IK-Ca. Phosphorylase b kinase (an exogenous calcium/calmodulin-dependent kinase) reduces IA, but whether IK-Ca and ICa are changed in the manner of associative training is not yet known. Another protein kinase present in high concentrations in both mammalian brain and molluscan nervous systems is protein kinase C, which is both calcium- and phospholipid-sensitive. We now present evidence that activation of protein kinase C by the tumour promoter phorbol ester (PDB) and intracellular injection of the enzyme induce conductance changes similar to those caused by associative training in Hermissenda B cells (that is a reduction of IA and IK-Ca, and enhancement of ICa). These results represent the first direct demonstration that protein kinase C affects membrane K+ ion conductance mechanisms.

Animals↗
PubMed1995

Interaction of smooth muscle caldesmon with calmodulin mutants.

The interaction of avian smooth muscle caldesmon with calmodulin (CaM) was investigated by studying the ability of selected mutant calmodulins to induce fluorescence changes in caldesmon. Different types of CaM mutants were used including point charge mutants, cluster mutations, and mutations which alter the calcium binding of CaM. The caldesmon binding properties were only slightly affected by E84K-CaM or by the double mutation E84Q/E120Q-CaM. Affinity of calmodulin to caldesmon was decreased 2-4 times by point mutation G33V-CaM, double mutation E84K/E120K-CaM, deletion of residues 82-84, and by cluster mutations DEE118-120-->KKK or EEE82-84-->KKK. Mutations of the first (E31A-CaM) and the second (E67A-CaM) calcium binding sites reduced the affinity of calmodulin to caldesmon by at least 5-fold; in addition these calmodulin mutants exhibited smaller changes in the fluorescence spectra of caldesmon. Simultaneous mutation of the two negatively charged clusters of calmodulin EEE82-84-->KKK and DEE118-120-->KKK resulted in a more than 15-fold decrease in the affinity of calmodulin for caldesmon. The data indicate that charged and uncharged amino acids in both halves of CaM play an important role in the binding of calmodulin to caldesmon, and that Ca2+ binding must be maintained in the amino-terminal sites for maximal interaction with caldesmon.

Animals↗
PubMed1977

Fourth expansion and glucose perturbation of the Dictyostelium kinetic model.

The kinetic model of carbohydrate metabolism has been expanded to include: (a) the accumulation of alpha and beta-cellulose, insoluble cell-wall glycogen and mucopolysaccharide; (b) the role of RNA turnover as a source of carbon for end-product synthesis and as a buffer regulating the level of uridine nucleotides in this metabolic network; and (c) the role of purine-nucleoside phosphorylase, 5'-AMP nucleotidase, nucleosidediphosphate kinase and polynucleotide phosphorylase. One of many predictions based on this model is that cells differentiating in the presence of glucose will produce sorocarps with an abnormally high trehalose to cellulose ratio. External perturbation of either the model or of developing cells by glucose increases the levels of sorocarp trehalose and glycogen, 5-fold and 6-fold respectively. Evaluation of the experimental data and the simulation analyses have allowed several predictions to be made concerning the compartmentation of metabolites and the permeability of cells to glucose during differentiation.

Carbohydrate Metabolism↗
PubMed1986

Domain organization of chicken gizzard myosin light chain kinase deduced from a cloned cDNA.

Myosin light chain kinases (MLCK) are the most studied of the calmodulin-activated enzymes; however, minimal sequence information is available for the smooth muscle form of the enzyme. The production of an antibody against the enzyme and the use of expression vectors for constructing cDNA libraries have facilitated the isolation of a cDNA for this kinase. The derived amino sequence was found to contain a region of high homology (54%) to the rabbit skeletal muscle enzyme and also very significant homology (35%) to the catalytic subunit of phosphorylase b kinase and cGMP-dependent protein kinase. All of these homologies were found in the known catalytic domains of these enzyme, thus enabling us to predict the location of the catalytic domain for the chicken gizzard myosin light chain kinase. Within the catalytic domain a consensus sequence for an ATP-binding site was located. Subcloning and expression of different regions of the cDNA defined a 192 base pair fragment coding for the calmodulin-binding domain of MLCK. Both of the cAMP-dependent protein kinase phosphorylation sites were identified by sequence homology. A linear model for MLCK is presented placing the various domains in relative position. Northern blot analysis and S1 protection and mapping experiments have revealed that the mRNA for MLCK is 5.5 kilobases in length, but there also exists a second mRNA of 2.7 kilobases that shares a high degree of homology with about 520 base pairs at the 3' end of the cDNA for MLCK.

Amino Acid Sequence↗
PubMed2000

Detection of kinases that phosphorylate 14-3-3 binding sites of Raf-1 using in situ gel kinase assay.

Raf-1 is a serine/threonine protein kinase that plays a critical role in mitogenic signal transduction. Raf-1 activation requires 14-3-3 binding to Raf-1 as an essential step. This binding is regulated through phosphorylation of Ser259 and Ser621 of Raf-1, each constituting part of the consensus motif for the binding of Raf-1 to 14-3-3. However, Raf-1 kinase kinase(s) that phosphorylates these sites remains unknown. In this report, we detected Raf-1 kinase kinase activity using recombinant glutathione-S-transferase-Raf-1 fusion proteins as substrate of in situ gel kinase assay. Ser259 was phosphorylated by a kinase with a molecular weight of 90 kDa, which was suggested to be Rsk judging from the molecular size, the time course of activation after EGF stimulation and the elution pattern from an anion-exchange column. The Raf-1 fragment containing Ser621 was phosphorylated by kinases with molecular weights of 85, 60, 50 and 48 kDa but not by the kinase that phosphorylates Ser259. These results suggest that although Ser259 and Ser621 lie in the same amino acid sequence motif for 14-3-3 binding, these two regulatory sites for this binding are phosphorylated by different protein kinases.

Animals↗
PubMed1982

Regulation of the biosynthesis of CoA at the level of pantothenate kinase.

1. Pantothenate kinase, which is present in cytosol, was studied in preparations from livers of rats fed normal or clofibrate-enriched diets. Effects of CoA, dephospho-CoA and different acyl-CoA derivatives on this enzyme activity were examined in vitro. 2. With partially purified pantothenate kinase or crude particle-free supernatant from the liver of normal or clofibrate-treated rats, Km for pantothenic acid was 0.016 mmol/l at the pH optimum 6.1. 3. Acetyl-CoA, propionyl-CoA, malonyl-CoA and other short-chain acyl-CoA derivatives were strong inhibitors of pantothenate kinase, with Ki in the range 0.001-0.003 mmol/l. The mechanism of inhibition appeared to be of an uncompetitive type. 4. Free CoA has been held to be the main regulator of pantothenate kinase. We found, however, that free CoASH, dephospho-CoA and long-chain acyl-CoA (with Ki 0.003-0.08 mmol/l) were less efficient inhibitors than acetyl-CoA. 5. With pantothenate kinase from clofibrate-treated animals, all inhibitors were less potent. This was most pronounced when the enzyme was assayed in a crude supernatant fraction, possibly because the inhibitors were degraded and/or protein bound. Such a reduction of normal inhibition may contribute to the increased biosynthesis of CoA previously observed during clofibrate treatment. 6. Fasting or diabetes leads to an increase of long-chain acyl-CoA and total CoA in the liver. The increase of CoA has been explained by increased acylation of CoA, and thereby reduced feed-back inhibition by free CoASH at the pantothenate kinase level. We propose another explanation. In these metabolic states, the cytosolic pool of acetyl-CoA is decreased. Since pantothenate kinase is present only in the cytosol, its activity will be released and the biosynthesis of CoA will increase. 7. Acetyl-CoA is probably a more important physiological regulator of pantothenate kinase activity than is free CoASH.

Acetyl Coenzyme A↗