Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A potent inhibitor of protein kinase C (PKC), inhibitor protein-1 (KCIP-1), isolated from sheep brain has been shown to consist of eight isoforms by reverse-phase HPLC. Direct protein sequence analysis has revealed these to be the same as those of 14-3-3 protein, described as an activator of tyrosine and tryptophan hydroxylases involved in neurotransmitter biosynthesis. The N-termini of KCIP-1 isoforms were shown to be acetylated, and secondary structure predictions revealed a high degree of alpha-helix with an amphipathic nature. KCIP-1 showed no inhibitory activity towards protein kinase M (the catalytic fragment of PKC) and had no effect on the activities of three other protein kinases, cAMP-dependent protein kinase, Ca2+/calmodulin-dependent protein kinase II and casein kinase 2. Four forms of KCIP-1 were shown to be substrates for PKC in vitro, but none were phosphorylated by the other protein kinases mentioned above.
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PMID:Multiple isoforms of a protein kinase C inhibitor (KCIP-1/14-3-3) from sheep brain. Amino acid sequence of phosphorylated forms. 131 96

The 14-3-3 proteins are a family of acidic proteins found mainly in the brain and are suggested to have a role in monoamine synthesis based on their ability to activate tyrosine and tryptophan hydroxylases in the presence of type II Ca2+/calmodulin-dependent protein kinase. Recently, however, it has been demonstrated that a member of the 14-3-3 family, termed Exo1, stimulates Ca(2+)-dependent exocytosis in permeabilized adrenal chromaffin cells, suggesting that this protein family may influence the protein kinase C-mediated control of Ca(2+)-dependent exocytosis. Here we show that the 14-3-3 proteins activate protein kinase C at about 2-fold more than the known level of the activated protein kinase, i.e. the activity of protein kinase C in the presence of Ca2+ and phospholipids. This raises the possibility that the cellular activity of protein kinase C is regulated by diverse members of the 14-3-3 family and that the reported ability of Exo1 to reactivate Ca(2+)-dependent exocytosis is based on its stimulatory effect on protein kinase C activity. The 14-3-3 family, therefore, appears to be a multifunctional regulator of cell signalling processes mediated by two types of Ca(2+)-dependent protein kinase, protein kinase C and type II calmodulin-dependent protein kinase.
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PMID:Activation of protein kinase C by the 14-3-3 proteins homologous with Exo1 protein that stimulates calcium-dependent exocytosis. 149 18

Activation of tyrosine and tryptophan hydroxylases, key enzymes for the catecholamine and serotonin biosynthesis, requires Ca2+/calmodulin-dependent protein kinase II and 14-3-3 protein which comprises a family of, at least, seven polypeptides in the bovine. Here we show that the amino acid sequence of the rat 14-3-3 eta chain deduced from the nucleotide sequence is completely identical to that of bovine counterpart. Using in situ hybridization the expression of mRNA for this protein is detected not only in the monoamine-synthetic neurons but also in many other discrete nuclei which synthesize neither catecholamine nor serotonin. The highly conservative structure between mammalian species and wider expression of this protein than expected in the central nervous system suggest that the 14-3-3 protein exerts some, though yet to be defined, functions fundamental to neuronal activities other than activation of the monoamine biosynthesis.
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PMID:Molecular cloning of cDNA to rat 14-3-3 eta chain polypeptide and the neuronal expression of the mRNA in the central nervous system. 164 68

Tyrosine and tryptophan hydroxylases are the key enzymes in the regulation of catecholamine and serotonin levels in neurons and other endocrine cells. Among the mechanisms proposed for the modulation of activity, phosphorylation of the enzyme is believed to be of functional significance with respect to the stimulus-response coupling, but the precise mechanism is unknown. Here, we show the existence of multiple, distinct forms of the 14-3-3 activator protein, a neuronal protein essential for activation of tyrosine and tryptophan hydroxylases by Ca2+/calmodulin-dependent protein kinase type II. Bovine brain 14-3-3 protein was resolved by reversed-phase chromatography into seven polypeptides (alpha to eta), all of which were active towards tryptophan hydroxylase when the renatured preparations were assayed in the presence of Ca2+, calmodulin and the protein kinase. Determination of the amino acid sequences of the beta and gamma chains and comparison of the sequences with the previously determined sequence of the eta chain revealed that these molecules are highly homologous, and share a common structural feature in containing an extremely acidic C-terminal region predicted as a domain for interaction with the phosphorylated hydroxylases. Northern blot analysis indicated that the beta, gamma and eta chain are expressed abundantly in the brain; however, these polypeptides appear to be expressed with different tissue specificities because gamma mRNA is found only in the brain, while lower levels of beta and eta mRNAs are detected in several other tissues. These findings suggest the involvement of a diverse family of the activator protein in the stimulus-coupled, Ca2(+)-dependent regulation of monoamine biosynthesis.
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PMID:Distinct forms of the protein kinase-dependent activator of tyrosine and tryptophan hydroxylases. 167 Nov 2

Synapsin I is a major nerve terminal-specific phosphoprotein. It consists of a hydrophobic head region containing one phosphorylation site for either cAMP-dependent protein kinase or Ca2+/calmodulin-dependent protein kinase I and of a basic and elongated tail region containing two phosphorylation sites for Ca2+/calmodulin-dependent protein kinase II. The steady-state emission spectrum of synapsin I was centered at 330 nm and was markedly red shifted upon denaturation, as expected for tryptophan residues segregated from the external aqueous environment in native conditions. Quenching studies showed a low accessibility of synapsin I tryptophans at low ionic strength which was further decreased by exposure to 200 mM NaCl but not significantly affected by phosphorylation. The intrinsic fluorescence of synapsin I was resolved into three major decay components with lifetimes of about 0.2, 3, and 7 ns. Upon phosphorylation of synapsin I on the tail sites, the spectra associated with the intermediate and long lifetimes were shifted to the red region, while the spectrum associated with the short lifetime was shifted to the blue region, in the absence of significant changes of the lifetimes. Phosphorylation of synapsin I on the head site was less effective. The anisotropy decay of synapsin I labeled with the long-living chromophore pyrene on Cys-223 was also analyzed. A shorter rotational correlation time was found for the tail phosphorylated form (corresponding to a Stokes radius of 41-42 A) than for the dephosphorylated or for the head phosphorylated form (corresponding to a Stokes radius of 60-63 A). The data suggest that phosphorylation of the tail sites induces changes in the conformation and hydrodynamic properties of synapsin I which may play a role in the regulation of the molecular interactions of synapsin I within the nerve terminal.
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PMID:Time-resolved fluorescence study of the neuron-specific phosphoprotein synapsin I. Evidence for phosphorylation-dependent conformational changes. 211 21

The 14-3-3 protein is a family of acidic proteins present exclusively in the brain and is believed to have a function in monoamine biosynthesis because of its ability to activate tyrosine hydroxylase and tryptophan hydroxylase in the presence of Ca2+/calmodulin-dependent protein kinase type II. In this study, we resolved bovine brain 14-3-3 protein into seven polypeptide components by means of reversed-phase chromatography and determined the amino acid sequence of one of these components (eta chain) by cloning its cDNA from a bovine cerebellum cDNA library. The eta-chain mRNA is 1.8 kilobases long and encodes a polypeptide of 246 amino acids and Mr 28,221. Computer-assisted analysis of the sequence indicates that the eta chain exhibits no internal sequence repeats, nor does it have significant sequence similarity to other proteins with known amino acid sequence. However, the eta chain appears to consist of two structural regions that are distinguishable in their clearly different charge characteristics: the almost neutral amino-terminal region and the strongly acidic carboxyl-terminal region. The structural features of the eta chain and the domain organization of tyrosine and tryptophan hydroxylases suggest that the 14-3-3 protein binds to the regulatory domain of the phosphorylated hydroxylases through its acidic carboxyl-terminal region and activates the hydroxylases by inducing an active conformation.
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PMID:Molecular cloning of cDNA coding for brain-specific 14-3-3 protein, a protein kinase-dependent activator of tyrosine and tryptophan hydroxylases. 290 23

In the course of determining the primary structure of rabbit skeletal muscle myosin light chain kinase (MLCK; ATP:protein phosphotransferase, EC 2.7.1.37) a peptide fragment was obtained that appears to represent the calmodulin-binding domain of this enzyme. Low concentrations of the peptide inhibited calmodulin activation of MLCK (Ki congruent to 1 nM). The peptide was not associated with a catalytically active, calmodulin-independent form of MLCK that was obtained by limited proteolysis. The peptide is 27 residues in length and represents the carboxyl terminus of MLCK. The sequence of the peptide shows no significant homology with any known protein sequence. The peptide contains one tryptophanyl residue and a high percentage of basic and hydrophobic residues, but no acidic or prolyl residues. Much of the sequence has a high probability of forming alpha helix. A chemically synthesized peptide has been prepared to study the interactions of the peptide and calmodulin in more detail. The intrinsic tryptophan fluorescence of the synthetic peptide shows a significant enhancement (approximately equal to 45%) in the presence of Ca2+ and calmodulin; fluorescence enhancement is maximal at a peptide:calmodulin stoichiometry of 1:1. Calmodulin-Sepharose affinity chromatography in the presence of 2 M urea indicates that the interaction of peptide and calmodulin is Ca2+-dependent. The results of these studies indicate that the catalytic and calmodulin-binding domains of MLCK represent distinct and separable regions of the protein. In addition, the results provide a basis for future studies of the molecular and evolutionary details of calmodulin-dependent enzyme regulation.
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PMID:Identification of the calmodulin-binding domain of skeletal muscle myosin light chain kinase. 385 14

The first step in the biosynthesis of melatonin in the pineal gland is the hydroxylation of tryptophan to 5-hydroxytryptophan. A cDNA of human tryptophan hydroxylase (TPH) was cloned from a library of human pineal gland and expressed in Escherichia coli. This cDNA sequence is identical to the cDNA sequence published from the human carcinoid tissue [1]. This human pineal hydroxylase gene encodes a protein of 444 amino acids and a molecular mass of 51 kDa estimated for the purified enzyme. Tryptophan hydroxylase from human brainstem exhibits high sequence homology (93% identity) with the human pineal hydroxylase. The recombinant tryptophan hydroxylase exists in solution as tetramers. The expressed human pineal tryptophan hydroxylase has a specific activity of 600 nmol/min/mg when measured in the presence of tetrahydrobiopterin and L-tryptophan. The enzyme catalyzes the hydroxylation of tryptophan and phenylalanine at comparable rates. Phosphorylation of the hydroxylase by protein kinase A or calmodulin-dependent kinase II results in the incorporation of 1 mol of phosphate/mol of subunit, but this degree of phosphorylation leads to only a modest (30%) increase in BH(4)-dependent activity when assayed in the presence of 14-3-3. Rapid scanning ultraviolet spectroscopy has revealed the formation of the transient intermediate compound, 4alpha-hydroxytetrahydrobiopterin, during the hydroxylation of either tryptophan or phenylalanine catalyzed by the recombinant pineal TPH.
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PMID:Cloning and expression of recombinant human pineal tryptophan hydroxylase in Escherichia coli: purification and characterization of the cloned enzyme. 1052 50