Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We compared the relative amounts and properties of cyclic adenosine 3':5'-monophosphate (cAMP)-binding proteins in surgical specimens of Wilms' tumor and normal kidney. Cytosolic fractions of both tissues contained type I and type II isozymes of cAMP-dependent protein kinase (adenosine triphosphate: protein phosphotransferase, EC 2.7.1.37). Among tumor samples, the mean ratio of type I to type II cAMP-binding activity was 2.76 +/- 0.52 (S.D.) contrasted with 1.36 +/- 0.23 for normal kidney (p less than 0.001). The total soluble cAMP-binding activities in normal and malignant tissues differed only slightly. Photoaffinity labeling of cytosol from either tissue, using cyclic adenosine 3':5'-[8-azido-32P]monophosphate, disclosed three cAMP-binding proteins (Mr 47,000, 51,000, and 55,000) that were identified as regulatory subunits of the holoenzyme. Three lower-molecular-weight proteins with unknown function were considered to be proteolytic products of the larger proteins. The Mr 47,000 protein, a monomeric regulatory subunit of type I kinase, was clearly the dominant protein in tumor specimens, but it was much less abundant in normal kidney. The temperature sensitivities of the cAMP-binding proteins and their dissociation constants for cyclic adenosine 3':5'-[8-azido-32P]monophosphate incorporation did not differ appreciably between tumor and normal tissues. Wilms' tumor appears to have a full complement of regulatory subunits of cAMP-dependent protein kinase that are capable of normal cellular function.
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PMID:Distribution and properties of type I and type II binding proteins in the cyclic adenosine 3':5'-monophosphate-dependent protein kinase system in Wilms' tumor. 609 71

Calmodulin-activated protein kinase activity in the endoplasmic reticulum fraction of rat adipocytes was identified and characterized. The major endogenous protein substrate of the calmodulin-activated kinase activity has an apparent molecular weight of 54,000 as determined by sodium dodecyl sulfate gel electrophoresis. The calmodulin-activated component of the activity was saturated at 10 microM ATP. Calcium or calmodulin alone did not increase the activity, but the simultaneous presence of calcium and calmodulin increased activity three to four-fold. Half-maximal activation of this activity occurred at 8 microM Ca2+. The addition of increasing amounts of calmodulin caused a concentration-dependent activation in the presence of calcium, which was saturable at high calmodulin concentrations. Magnesium was required for activity, with half-maximal activity occurring at 230 microM. The antipsychotic drug trifluoperazine inhibited the activation of the protein kinase activity by calmodulin, but had a negligible effect on the basal activity. Half-maximal inhibition occurred at 63 microM. Phosphorylation of the 54,000 mol. wt band was independent of cAMP, cGMP and the combination of cAMP and cAMP-dependent protein kinase. Calmodulin-activated protein kinase phosphorylated both phosphoserine and phosphothreonine residues in the 54,000 mol. wt substrate. These experiments have partially characterized a calmodulin-activated protein kinase activity from adipocytes, which appears to be a unique activity of unknown function.
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PMID:Characterization of calmodulin-activated protein kinase activity of rat adipocyte endoplasmic reticulum fraction. 670 68

The present study has investigated the influence of arachidonate, endoperoxide analogs, and the calcium ionophore A23187 on platelet aggregation and on the phosphorylation of platelet proteins. Following stimulation of platelets by these agents a rapid increase in phosphorylation of three proteins was observed which began at the same time as the initial formation of platelet aggregates. These three proteins were the 260,000 dalton actin-binding protein, a 40,000 dalton protein in unknown function, and the 20,000 dalton myosin light chain. When extensive aggregation was reached, the extent of phosphorylation returned toward baseline. Pretreatment of platelets with aspirin completely inhibited both aggregation and protein phosphorylations induced by arachidonate, but had only partial inhibitory effects on endoperoxide analogs or A23187. Since endoperoxide analogs and A23187 may trigger endogenous production of prostaglandin endoperoxides and thromboxane A2, in addition to having a direct effect of their own, it is probable that the partial inhibition seen was due to inhibition of that component of their effect due to this endogenous production, though other effects of aspirin can not be entirely ruled out. Since recent evidence shows that phosphorylation of myosin light chain results from calcium stimulation of a protein kinase in the presence of calmodulin, the results are consistent with mobilization of calcium as the primary role of the arachidonate-endoperoxide-thromboxane pathway.
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PMID:Stimulation of platelet protein phosphorylation by arachidonic acid and endoperoxide analogs. 679 1

Myosin light chain kinase was purified > 100,000-fold to apparent homogeneity with a yield of 10% from bovine cardiac muscle. Sodium dodecyl sulfate gels of the purified kinase showed one stained band corresponding to a Mr of 94,000. The enzyme was activated > 10-fold in the presence of Ca2+ (apparent Ka = 0.6-1.2 microM) and calmodulin (apparent Ka = 3-5 nM). The purified enzyme had a specific activity of 20-30 mumol of phosphate transferred per min per mg from ATP to cardiac myosin light chain 2. One mole of phosphate was incorporated per 94,000 g of the kinase in the presence of Ca2+ and calmodulin or of cyclic AMP-dependent protein kinase or of both additions. In addition to myosin light chain kinase, a calmodulin-binding protein of unknown function was purified from bovine cardiac muscle. This protein had a Mr of 85,000, was composed of two dissimilar subunits (Mr of 61,000 and 15,000), and competed with myosin light chain kinase for calmodulin. The protein appears to be closely related to the calmodulin-binding protein I purified from brain.
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PMID:Purification of myosin light chain kinase from bovine cardiac muscle. 693 18

The complete DNA sequence of cosmid clone p59 comprising 37,549 bp derived from chromosome X was determined from an ordered set of subclones. The sequence contains 14 open reading frames (ORFs) containing at least 100 consecutive sense codons. Four of the ORFs represent already known and sequenced yeast genes: B645 is identical to the SME1 gene encoding a protein kinase, required for induction of meiosis in yeast, D819 represents the MEF2 gene probably encoding a second mitochondrial elongation factor-like protein, D678 is identical to the yeast GSH1 gene encoding gamma-glutamylcysteine synthetase and B746 is identical to the CSD3 gene, which plays an as yet unidentified role in chitin biosynthesis and/or its regulation. The deduced amino acid sequence of A550 is 63% identical to the Cc eta subunit of a murine TCP-1-containing chaperonin and more than 35% identical to thermophilic factor 55 from Sulfolobus shibatae, as well as to a number of proteins belonging to the chaperonin TCP-1 family. Open reading frame F551 exhibits homology to two regions of the DAL80 gene located on yeast chromosome XI encoding a pleiotropic negative regulatory protein. In addition, extensive homology was detected in three regions including parts of ORFs A560, B746/CSD3 and the incomplete ORF C852 to three consecutive ORFs of unknown function in the middle of the right arm of chromosome XI. Finally, the sequence contained a tRNA(Arg3) (AGC) gene.
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PMID:A 37.5 kb region of yeast chromosome X includes the SME1, MEF2, GSH1 and CSD3 genes, a TCP-1-related gene, an open reading frame similar to the DAL80 gene, and a tRNA(Arg). 748 51

The unusually large (approximately 600 to > 3000 kDa) myosin-associated proteins of the titin/twitchin superfamily are considered to be important cytoskeletal rulers for thick filament assembly in muscle. This function is maintained by approximately 60-240 modular fibronectin-type-III and immunoglobulin-C2 repeats in these proteins which further contain a protein serine/threonine kinase domain of unknown function. In this study, the bacterially expressed kinase domain of Aplysia twitchin was used in order to identify a potential physiological substrate. Addition of the recombinant kinase to Aplysia actomyosin preparations resulted in the specific phosphorylation of the 19-kDa myosin regulatory light chains. The twitchin kinase phosphorylated purified light chains on Thr15 in a region which shared a high degree of similarity with the phosphorylation site for vertebrate smooth muscle myosin light chain kinase. Peptide analogs of the twitchin substrate sequence and the similar sequence in vertebrate smooth muscle myosin light chains were phosphorylated with good kinetic properties. These data reveal the first potential substrate for any of the giant protein kinases and support a dual role of twitchin in molluscan muscle as a cytoskeletal protein as well as a myosin light chain kinase.
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PMID:Phosphorylation of myosin regulatory light chains by the molluscan twitchin kinase. 758 84

Liver plasma membranes originating from the sinusoidal, lateral and canalicular domains and 'early' and 'late' endosomes were prepared from rats injected with [32P]orthophosphate. The phosphorylated polypeptides in these subcellular fractions, resolved by gel electrophoresis, were analysed and compared with those obtained by in vitro phosphorylation of the fractions by endogenous protein kinases. The polypeptides phosphorylated in vitro were different in plasma membranes, endosomes and lysosomes. Three of the major phosphoproteins in the endocytic membranes were shown to be the polymeric immunoglobulin receptor, the beta subunit of the insulin receptor and the 550-kDa low-density-lipoprotein-receptor-related protein (LRP). An additional 35-kDa polypeptide of unknown function was a major phosphorylated component and thus emerges as a candidate marker protein of hepatic endosomes. Phosphoserine was shown to be the major amino acid phosphorylated in vitro in the phosphoproteins of endocytic membranes. The subcellular distribution in liver tissue of protein kinase activity was also investigated and activity shown to be recovered mainly in blood-sinusoidal and lateral plasma membranes; bile canalicular plasma membranes and endosomes contained low protein kinase activities. The results show that receptor phosphorylation is an 'early' event in endocytosis and the trafficking of ligands that is sustained especially in early endosomes in liver, and emphasizes the biochemical and thus functional distinctiveness of the plasma membrane and the endosomal and lysosomal compartments with regard to their population of phosphorylated proteins.
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PMID:Functional identification of three major phosphoproteins in endocytic fractions from rat liver. A comparative in vivo and in vitro study. 764 80

Deletion mutagenesis was used to identify sequences required for dimerization and enzymatic activity of the intracellular domain of the membrane guanylyl cyclase, GC-A. The intracellular domain of GC-A contains a protein kinase-like domain near its amino terminus, a guanylyl cyclase catalytic domain near its carboxyl terminus, and, between these domains, a region of unknown function predicted to form an amphipathic alpha-helix. Gel filtration analysis of deletion mutants of the GC-A intracellular domain suggested that a 43 amino acid sequence within the interdomain region was both necessary and sufficient for dimerization and was required for guanylyl cyclase catalytic activity. The ability of this sequence to mediate protein dimerization was confirmed in the yeast two-hybrid system, in which its fusion to the lexA DNA-binding domain and to the VP16 transcriptional activation domain led to their dimerization and consequent activation of a lexA-HIS3 gene. Thus, we have identified sequences responsible for dimerization of the intracellular domain of a guanylyl cyclase and shown that they are required for enzyme activity. Modulation of their interaction may be important in guanylyl cyclase activation.
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PMID:Identification of sequences mediating guanylyl cyclase dimerization. 771 74

Mammalian steroid receptors exist in hormone-free cells in a heterocomplex that contains the three heat shock proteins hsp90, hsp70 and hsp56. Some protein kinases, including pp60v-src and v-Raf, exist in similar cytosolic heterocomplexes containing hsp90 and a 50 kDa protein of unknown function, pp50. The four proteins--hsp90, hsp70, hsp56 and pp50--exist together in a heterocomplex independent of the presence of steroid receptors and protein kinases. Both the receptor and the protein kinase heterocomplexes can be formed by a protein folding-heterocomplex assembly system in reticulocyte lysate that carries out an hsp70-dependent attachment of the proteins to the preformed heat shock protein complex. Association of receptors with this structure occurs at the termination of receptor translation and is critical for maintenance of the receptors in a transcriptionally inactive state in the absence of hormone. We discuss how this preformed protein folding structure may be involved in the subsequent targeted trafficking of steroid receptors through the cytoplasmic space to the nucleus.
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PMID:Chaperone functions of the heat shock proteins associated with steroid receptors. 791 46

Protein kinase-related domains of unknown function are present in the JAK family of protein tyrosine kinases and in receptor/guanylyl cyclases. I used the yeast two-hybrid system to screen for proteins interacting with the kinase-like domain of the atrial natriuretic peptide (ANP) receptor/guanylyl cyclase. A yeast strain was constructed expressing a fusion of this kinase-like domain to the lexA DNA-binding domain and containing a HIS3 gene under the control of lexA upstream activating sequences. These yeast cells were transformed with a plasmid library of mouse embryo cDNA fragments fused to the VP16 transcriptional activation domain. Cells containing VP16-fusion proteins interacting with the lexA-kinase-like domain fusion protein were selected by growth in the absence of histidine. A partial-length cDNA clone isolated by using this approach encoded a protein that interacted specifically with the ANP-receptor protein kinase-like domain both in yeast cells and in vitro. Tissue-specific expression of a 2.2-kb mRNA hybridizing to this cDNA paralleled the known pattern of ANP-receptor mRNA expression. A full-length cDNA clone isolated from a rat lung library was predicted to encode a 55-kDa protein containing at its amino terminus a targeting domain that binds to the ANP-receptor kinase-like domain and containing at its carboxyl terminus a putative protein-serine phosphatase domain. This protein is a possible candidate for the phosphatase involved in desensitizing the ANP receptor. Targeting of regulatory proteins may be an important function of protein kinase-like domains.
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PMID:Targeting of a distinctive protein-serine phosphatase to the protein kinase-like domain of the atrial natriuretic peptide receptor. 797 12


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