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

The activity of the eukaryotic elongation factor 2 (eEF-2)-specific Ca(2+)- and calmodulin-dependent protein kinase III (CaM PK III) is regulated by phosphorylation. The kinase can be inactivated by treatment with alkaline phosphatase and subsequently reactivated by endogenous protein kinase. This kinase can be substituted for by the catalytic subunit of cAMP-dependent protein kinase but not by casein kinase II. The purified kinase preparation contains only one protein as judged by gel electrophoresis. This protein has a molecular mass of approximately 90 kDa and an isoelectric point of 5.2. Reactivation of the eEF-2 kinase is associated with the phosphorylation of this protein. The amino acid sequence obtained from the 90-kDa protein reveals substantial homology with that of murine heat shock protein 86 (HSP 86) a member of the HSP 90-family. Conventional preparations of HSP 90 contain an inactive eEF-2 kinase that could be activated after dephosphorylation and phosphorylation by the catalytic subunit of cAMP-dependent protein kinase.
J Biol Chem 1991 Sep 05
PMID:Phosphorylation regulates the activity of the eEF-2-specific Ca(2+)- and calmodulin-dependent protein kinase III. 188 75

Tissue-specific extinguisher 1 (TSE1) is a trans-acting locus on human chromosome 17 that down-regulates expression of seven liver genes in hepatoma x fibroblast hybrids. To study the mechanism by which TSE1 functions, we used subtractive cDNA hybridization to clone transcripts encoded within a 2-4 Mb segment of chromosome 17 that includes TSE1. High resolution mapping within this region indicated that 8 of 9 different human cDNAs so obtained were distinct from TSE1. The remaining cDNA clone mapped concordantly with TSE1 in a panel of fragment-containing hybrids. DNA sequencing indicated that this cDNA encoded regulatory subunit RI alpha of cAMP-dependent protein kinase, and RI alpha mRNA levels correlated with TSE1 activity in various hybrid lines. Stable transfection of wild-type or cAMP-binding mutant RI alpha alleles into hepatoma recipients produced an extinction phenotype indistinguishable from that encoded by human TSE1. We conclude that TSE1 encodes a regulatory subunit of protein kinase A whose activity differs in different cell types.
Cell 1991 Sep 06
PMID:Subtractive hybridization cloning of a tissue-specific extinguisher: TSE1 encodes a regulatory subunit of protein kinase A. 188 88

Agents that activate cAMP-dependent protein kinase (PKA) as well as agents that increase intracellular calcium induce the expression of certain immediate early genes (IEGs). Recently, it has been demonstrated that the same cis-acting element in the 5' region of the c-fos gene has the ability to mediate both cAMP- and calcium-induced c-fos expression in PC12 cells (Sheng, M., McFadden, G., and Greenberg, M. (1990) Neuron 4, 571-582). Here we demonstrate that both cAMP- and calcium-mediated induction of c-fos and egr1 are dependent on PKA activity. Addition of either depolarizing concentrations of KCl or the calcium ionophore, ionomycin, to PC12 cells increased the expression of both c-fos and egr1, but these inductions were dramatically reduced in three PKA-deficient cell lines, 123.7, AB.11, and A126-1B2. Furthermore, pretreatment of PC12 cells with 20 microM H89, a specific inhibitor of PKA, inhibited forskolin, dibutyryl cAMP, and KCl-induced c-fos and egr1 induction, while having no effect on NGF induction. Likewise, in the PKA-deficient cells, NGF or an activator of protein kinase C induced c-fos and egr1 normally. To determine if PKA deficiency modifies the ability of Ca2+ to activate calcium-dependent kinases, autophosphorylation of multifunctional Ca2+/calmodulin-dependent protein kinase (CaM kinase) in response to Ca2+ influx was determined. In parental PC12 cells, PC12 cells pretreated with H89, and PKA-deficient cell lines, CaM kinase was activated equivalently in response to KCl depolarization. These results suggest that PKA is not required for Ca(2+)-induced increase in CaM kinase activity and that the induction of IEGs in response to Ca2+ influx is PKA-dependent. Thus, the requirement for PKA resides at a point distal to the activation of calmodulin-dependent processes.
J Biol Chem 1991 Sep 15
PMID:Induction of immediate early genes by Ca2+ influx requires cAMP-dependent protein kinase in PC12 cells. 191 45

The substrate specificity of the cAMP-dependent protein kinase (cAPK) from Saccharomyces cerevisiae has been investigated using synthetic peptides corresponding to the local phosphorylation site sequence around Ser-230 in the yeast transcriptional activator ADR1. ADR1 is required for the expression of the glucose-repressible alcohol dehydrogenase. Yeast cAPK (encoded by the TPK1 gene) phosphorylated Ser-230 in the synthetic peptide ADR1-217-234, VRKRYLKKLTRRASFSAQ-NH2, with a Km of 5.3 microM compared with 46 microM for LRRASLG (Kemptide). Porcine heart cAPK phosphorylated the ADR1 peptide and Kemptide with the considerable lower Km values of 0.23 and 1.6 microM, respectively. These results indicate that the ADR1 peptide is an excellent substrate for cAPK. Both the yeast and mammalian protein kinases qualitatively shared a number of substrate specificity determinants in common involving residues on the proximal NH2-terminal side and up to the +4 position of the COOH-terminal side of the phosphoacceptor. The mammalian enzyme, however, had a much higher affinity for its substrates than did the yeast enzyme. In addition, the yeast and mammalian enzymes displayed several quantitative differences in their preferences for particular peptide substrates. In particular, the mammalian enzyme strongly preferred substrates with NH2-terminal extensions beyond the -4 position relative to the phosphoacceptor. These results suggest that all eukaryotic cAPKs recognize similar but not identical substrate specificity determinants. They also suggest that the different affinities for substrates that inhere to the individual enzymes could influence their physiological roles.
J Biol Chem 1991 Sep 25
PMID:Substrate specificities for yeast and mammalian cAMP-dependent protein kinases are similar but not identical. 191 32

Our purpose was to identify regulatory (R) subunits and their associations with catalytic (C) subunits to form cAMP-dependent protein kinase (A-kinase) holoenzymes in select porcine ovarian tissues during follicular differentiation. Soluble extracts of small and preovulatory follicles and corpora lutea (CL) were separated on DEAE-cellulose chromatography. R subunits were labeled with 8-N3[32P]cAMP or with [gamma-32P]ATP under RII autophosphorylation conditions and were identified by molecular weight (Mr) determination on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as well as cross-reactivity of unlabeled subunits with anti-R antibodies. A-kinase holoenzymes and C subunit-free R (free R) subunits were distinguished on the basis of DEAE elution position and sedimentation position on sucrose density gradient centrifugation of phosphotransferase and [3H]cAMP binding activities. In small and preovulatory follicles and CL we identified a minor peak of type I A-kinase containing RI alpha (Mr = 47,000) and a major peak of type II A-kinase holoenzyme containing two RII isoforms (Mr = 52,000 and 56,000). Notable amounts of free RI alpha eluted between the type I and II holoenzymes in all three tissues. Neither of the holoenzymes nor free RI alpha was regulated as a function of follicular differentiation or CL formation. In contrast, free RII subunits were moderately increased in preovulatory follicles relative to levels in small follicles and CL. We conclude that only the RII subunits are hormonally regulated in developing follicles, and in tissues which express both RI and RII subunits, the RII subunits preferentially associate with C subunits to form the dominant holoenzyme despite the presence of significant amounts of RI.
Mol Cell Endocrinol 1991 Sep
PMID:cAMP-dependent protein kinase isozymes in porcine follicles and corpora lutea. 195 84

The kappa-selective opioid peptide dynorphin A (DYN) inhibits neuronal adenylate cyclase activity and reduces neuronal voltage-dependent calcium currents. It is not yet known, however, whether the regulation of calcium channel activity is dependent on or independent of the adenylate cyclase/cAMP system. We used the whole-cell variation of the patch clamp technique to show that DYN reversibly reduced, in a naloxone-sensitive manner, calcium currents in acutely dissociated rat nodose ganglion neurons. DYN slowed the rate of current activation and had a greater effect on currents evoked from relatively negative holding potentials. These actions were mimicked by guanosine 5'-[gamma-thio]triphosphate, which activates GTP-binding proteins (G proteins), and were blocked by pretreatment with pertussis toxin, which inactivates Gi- and Go-type G proteins. In contrast, calcium currents recorded in the presence of the catalytic subunit of the cAMP-dependent protein kinase (AK-C), included in the recording pipette, increased in magnitude throughout the recording. DYN was applied to neurons before and after the effect of AK-C became apparent; the reduction of calcium currents by DYN was greater in the presence of AK-C than in its absence. We conclude that the acute reduction of neuronal calcium currents by DYN occurred by means of activation of pertussis toxin-sensitive Gi- or Go-type G proteins. The persistence of the action of DYN in the presence of AK-C indicates, however, that this effect was independent of a reduction of the activity of the adenylate cyclase/cAMP system and suggests in addition that phosphorylated channels may be preferentially inhibited by DYN.
Proc Natl Acad Sci U S A 1990 Sep
PMID:Dynorphin A and cAMP-dependent protein kinase independently regulate neuronal calcium currents. 197 50

A platelet cDNA expression library was screened with the monoclonal antibody M90, which recognizes a specific epitope on RAS-encoded p21 proteins (amino acids 107-130). DNA sequence analysis of one clone revealed that it encoded a partial amino acid sequence of a protein closely related to RAP2, which we have named RAP2B. A repeated screening of the platelet cDNA library with an internal Ava I fragment of the RAP2B cDNA allowed the isolation of a full-length cDNA for the RAP2B sequence. RAP2B is 90% identical to RAP2 at the amino acid level with the most variability at the carboxyl terminus of the protein. Oligonucleotides were synthesized to complete the amino acid sequence of the RAP2B protein and the entire sequence was expressed in Escherichia coli. Analysis of crude soluble extracts indicated that RAP2B was a Mr 22,000 protein that specifically bound GTP on blots. Moreover, incubation of similar extracts with the catalytic subunit of cAMP-dependent protein kinase did not cause phosphorylation of RAP2B, as had been observed for the closely homologous proteins, RAP1A and RAP1B. These results suggest that RAP2B, like the other RAP proteins, is a low molecular weight GTP-binding protein in human platelets.
Proc Natl Acad Sci U S A 1990 Sep
PMID:RAP2B: a RAS-related GTP-binding protein from platelets. 211 48

The synapsins are a family of neuron-specific phosphoproteins that selectively bind to small synaptic vesicles in the presynaptic nerve terminal. Using the cDNA encoding rat synapsin IIb, we employed an Escherichia coli expression system to synthesize a variety of fusion proteins containing a truncated protein A linked to different portions of the NH2-terminal region of synapsin II. The recombinant proteins were purified by IgG-Sepharose chromatography and tested in vitro for their ability to bind to purified synaptic vesicles. These experiments identified a region between amino acids 43 and 121 of the amino-terminal portion of synapsin II which binds to synaptic vesicles. Mild trypsinization of synaptic vesicles reduces binding of recombinant proteins to synaptic vesicles, suggesting that the interaction between synapsin II and the vesicles is in part mediated by a synaptic vesicle protein. The 42 NH2-terminal amino acids of synapsin II are not necessary for binding to synaptic vesicles, although this domain contains the phosphorylation site for cAMP-dependent protein kinase.
J Biol Chem 1990 Sep 25
PMID:Synapsin II. Mapping of a domain in the NH2-terminal region which binds to small synaptic vesicles. 211 8

The transcription regulation of many hormone genes is modulated by intracellular second messengers such as cAMP. The cAMP response element binding protein, CREB, binds to the 8 base pair CRE enhancer, TGACGTCA, that is found in the 5'-flank of certain genes including those for somatostatin and the alpha-subunit of human chorionic gonadotropin. The recent characterization of CREB and CREB-related cDNA clones, combined with Southwesterns and Northern blot analyses, reveals a family of transcription factors that dimerize via a leucine zipper motif and bind to the CRE through positively charged basic regions. The CREB cDNA encoding a 327 residue protein is transcriptionally activated via phosphorylation by protein kinases, including the cAMP-dependent protein kinase-A.
Metabolism 1990 Sep
PMID:Characterization of a cAMP-regulated enhancer-binding protein. 214 88

Treatment of PC12h cells with nerve growth factor (NGF) induced a transient increase in the phosphorylation of a 35,000-dalton protein. This transient increase was observed also when extracts of NGF-treated cells were incubated with [gamma-32P]ATP. In the intact-cell phosphorylation system, treatment with N,2'-dibutyryladenosine 3',5'-cyclic monophosphate (dBcAMP) or 12-O-tetradecanoylphorbol 13-acetate (TPA) also induced a transient increase in the phosphorylation of the 35,000-dalton protein, but the effect was less than that of NGF. An effect comparable to that of NGF was obtained by the combination of dBcAMP and TPA. Pretreatment of PC12h cells with dBcAMP plus TPA for 3 days, which deprived the cells of their ability to respond to a rechallenge with dBcAMP, TPA, or dBcAMP plus TPA by increasing the rate of 35,000-dalton protein phosphorylation, caused only a slight attenuation of the NGF effect, directly indicating a minimal role of cyclic AMP (cAMP)-dependent protein kinase and protein kinase C in the mechanism of the NGF action. Pretreatment of the cells with K-252a, a protein kinase inhibitor, at a concentration of 300 nM almost completely blocked the action of NGF, but scarcely affected the action of dBcAMP, TPA, or dBcAMP plus TPA in intact-cell phosphorylation experiments. This NGF-sensitive 35,000-dalton protein was a ribosomal protein and identified as ribosomal protein S6. The results lead us to conclude that NGF activates some NGF-sensitive component(s), probably some specific protein kinase(s) other than cAMP-dependent protein kinase or protein kinase C, which is suppressed by K-252a and directly or indirectly activates a 35,000-dalton protein kinase(s) [S6 kinase(s)] to increase the rate of phosphorylation of the 35,000-dalton ribosomal protein (S6).
J Neurochem 1990 Sep
PMID:Nerve growth factor-induced transient increase in the phosphorylation of ribosomal protein S6 mediated through a mechanism independent of cyclic AMP-dependent protein kinase and protein kinase C. 216 78


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