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)

L-type pyruvate kinase (EC 2.7.1.40) purified from pig liver was ADP-ribosylated by incubation with NAD and ADP-ribosyltransferase purified from hen liver nuclei. Maximal incorporation of the ADP-ribose moiety from NAD into the L-type pyruvate kinase was 0.98 mol/mol of subunit. The Km values for NAD and L-type pyruvate kinase were 0.17 mM and 9.7 microM, respectively. ADP-ribosylation of the L-type pyruvate kinase resulted in suppression of the subsequent phosphorylation catalyzed by cAMP-dependent protein kinase. The ADP-ribosylation-induced suppression of phosphorylation of the L-type pyruvate kinase also resulted in suppression of the phosphorylation-induced inactivation. Amino acid analysis, after exhaustive sequential digestion of ADP-ribosyl-L-type pyruvate kinase with pepsin, aminopeptidase M and carboxy-peptidase B showed arginine to be the ADP-ribose-accepting amino acid. These results together with finding of the ADP-ribosyltransferase activity in mammalian liver cytosol (Moss, J. and Stanley, S.J. (1981) J. Biol. Chem. 256, 7830-7833) suggest that ADP-ribosylation may participate in the regulation of the L-type pyruvate kinase activity through changes in the rate of phosphorylation.
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PMID:ADP-ribosylation suppresses phosphorylation of the L-type pyruvate kinase. 334 9

Both the triple-helical and denatured forms of nonfibrillar bovine dermal type I collagen were tested as substrates for the catalytic subunit of cAMP-dependent protein kinase in an in vitro reaction. Native, triple-helical collagen was not phosphorylated, but collagen that had been thermally denatured into individual alpha chains was a substrate for the protein kinase. Catalytic subunit of cAMP-dependent protein kinase phosphorylated denatured collagen to between 3 to 4 mol of phosphate/mol of (alpha 1(I)2 alpha 2(I). Pepsin-solubilized and intact collagens were phosphorylated similarly, as long as each was in a nonhelical conformation. The first 2 mol of phosphate incorporated into type I collagen by the protein kinase were present in the alpha 2(I) chain. The alpha 1(I) chain was only phosphorylated during long incubations in which the stoichiometry exceeded 2 mol of phosphate/mol of (alpha 1(I)2 alpha 2(I). Phosphoserine was the only phosphoamino acid identified in collagen that had been phosphorylated to any degree by the protein kinase. The 2 mol of phosphate incorporated into the alpha 2(I) chain were localized to the alpha 2(I)CB4 cyanogen bromide fragment. The catalytic subunit of cAMP-dependent protein kinase phosphorylated denatured pepsin-solubilized collagen with a Km of 8 microM and a Vmax of approximately 0.1 mumol/min/mg of enzyme. Denatured, but not triple-helical, type I collagen was also phosphorylated by cGMP-dependent protein kinase, although it was a poorer substrate for this enzyme than for the cAMP-dependent protein kinase. Collagen was not a substrate for phospholipid-sensitive Ca2+-dependent protein kinase. These results suggest the potential for nascent alpha chains of type I collagen to be susceptible to phosphorylation by cAMP-dependent protein kinase in vivo prior to triple-helix formation. Such a phosphorylation of collagen could be relevant to the action of cAMP to increase the intracellular degradation of newly synthesized collagen.
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PMID:In vitro phosphorylation of type I collagen by cyclic AMP-dependent protein kinase. 395 36

Various proteins/enzymes obtained commercially were tested for the presence of endogenously nitrated tyrosine by Western blot analysis omitting reducing agent in the step of SDS-PAGE. Histones II-S and VIII-S, IgG, cAMP-dependent protein kinase (PKA), phosphorylase b, and phosphorylase kinase exhibited strong immunoreactive bands. Histone VI-S, glycogen synthase, lactate dehydrogenase, actin, thyroglobulin, and macroglobulin exhibited moderate immunoreactivity. Histone III-S, casein, acetyl cholinesterase, DNase I, and lipase had only traceable immunoreactivity. Whereas histone VII-S, pyruvate kinase, trypsin, pepsin, chymotrypsin, protease IV, and protease XIII, and glutathione S-transferase lacked immunoreactivity. A variation of immunoreactivity between hypertensive and normaltensive rat hearts was found in the histone-agarose fractions of crude extracts. Additionally, nitrotyrosine immunoreactivity was observed in non-mammalian organisms including Eschericia coli, Saccharomyces cerevisiae and Triticum vulgaris. Upon the treatment of 15 microM peroxynitrite (PN), strong oxidant derived from nitric oxide (NO), the apparent Km of PKA for cAMP increased from approximately 10(-8) to 10(-6) M. The results imply that the varied nitration of tyrosine residues in proteins/enzymes may occur as a post-translational modification in vivo, and such discriminative nitration may be vital in PN/NO-regulated signal transduction cascade.
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PMID:Protein nitration. 1119 83

cAMP-dependent protein kinase (cAPK) is a key component in numerous cell signaling pathways. The cAPK regulatory (R) subunit maintains the kinase in an inactive state until cAMP saturation of the R-subunit leads to activation of the enzyme. To delineate the conformational changes associated with cAPK activation, the amide hydrogen/deuterium exchange in the cAPK type IIbeta R-subunit was probed by electrospray mass spectrometry. Three states of the R-subunit, cAMP-bound, catalytic (C)-subunit bound, and apo, were incubated in deuterated water for various lengths of time and then, prior to mass spectrometry analysis, subjected to digestion by pepsin to localize the deuterium incorporation. High sequence coverage (>99%) by the pepsin-digested fragments enables us to monitor the dynamics of the whole protein. The effects of cAMP binding on RIIbeta amide hydrogen exchange are restricted to the cAMP-binding pockets, while the effects of C-subunit binding are evident across both cAMP-binding domains and the linker region. The decreased amide hydrogen exchange for residues 253-268 within cAMP binding domain A and for residues 102-115, which include the pseudosubstrate inhibitory site, support the prediction that these two regions represent the conserved primary and peripheral C-subunit binding sites. An increase in amide hydrogen exchange for a broad area within cAMP-binding domain B and a narrow area within cAMP-binding domain A (residues 222-232) suggest that C-subunit binding transmits long-distance conformational changes throughout the protein.
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PMID:Dynamics of cAPK type IIbeta activation revealed by enhanced amide H/2H exchange mass spectrometry (DXMS). 1266 31

cAMP-dependent protein kinase (cAPK) is a heterotetramer containing a regulatory (R) subunit dimer bound to two catalytic (C) subunits and is involved in numerous cell signaling pathways. The C-subunit is activated allosterically when two cAMP molecules bind sequentially to the cAMP-binding domains, designated A and B (cAB-A and cAB-B, respectively). Each cAMP-binding domain contains a conserved Arg residue that is critical for high-affinity cAMP binding. Replacement of this Arg with Lys affects cAMP affinity, the structural integrity of the cAMP-binding domains, and cAPK activation. To better understand the local and long-range effects that the Arg-to-Lys mutation has on the dynamic properties of the R-subunit, the amide hydrogen/deuterium exchange in the RIIbeta subunit was probed by electrospray mass spectrometry. Mutant proteins containing the Arg-to-Lys substitution in either cAMP-binding domain were deuterated for various times and then, prior to mass spectrometry analysis, subjected to pepsin digestion to localize the deuterium incorporation. Mutation of this Arg in cAB-A (Arg230) causes an increase in amide hydrogen exchange throughout the mutated domain that is beyond the modest and localized effects of cAMP removal and is indicative of the importance of this Arg in domain organization. Mutation of Arg359 (cAB-B) leads to increased exchange in the adjacent cAB-A domain, particularly in the cAB-A domain C-helix that lies on top of the cAB-B domain and is believed to be functionally linked to the cAB-B domain. This interdomain communication appears to be a unidirectional pathway, as mutation of Arg230 in cAB-A does not effect dynamics of the cAB-B domain.
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PMID:Dissecting interdomain communication within cAPK regulatory subunit type IIbeta using enhanced amide hydrogen/deuterium exchange mass spectrometry (DXMS). 1293 Sep 97