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

The adenosine 3",5"-monophosphate (cAMP)-dependent ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity of cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) from bovine heart is characterized. That the ATPase activity is intimately associated with the catalytic subunit of the enzyme is suggested by the following: (i) the similar dependences of ATPase and protein kinase activities on cAMP; (ii) the dissociation of ATPase activity from the holoenzyme on addition of cAMP and its co-elution with the catalytic subunit on gel filtration chromatography; (iii) the similarity of the relative effectiveness of divalent metal ions in ATPase and protein kinase catalysis; and (iv) the correspondence of kinetically determined Km(MgATP) and Ki(MgADP) values with thermodynamic dissociation constants determined by equilibrium dialysis. The hydrolysis of ATP is stimulated 10- to 20-fold by cAMP in the holoenzyme. The molar specific activity of the catalytic subunit ATPase is approximately 0.7 min-1 with Km(MgATP) = 5 muM. MgADP is a competitive inhibitor of the reaction with a Ki value of approximately muM. The order of the relative effectiveness of metal ions for both ATPase and peptide kinase activities is Mg2+ greater than Mn2+ greater than Ca2+. A possible interpretation of these observations is that the role that the metal ion plays is more directly manifested in bond-breaking than in bond-forming.
 ...
PMID:Cyclic AMP-dependent ATPase activity of bovine heart protein kinase. 21 18

Sarcomplasmic reticulum from rabbit fast skeletal muscle contains intrinsic protein kinase activity (ATP:protein phosphotransferase, EC 2.7.1.37) and a substrate. The protein kinase activity was Mg2+ dependent and could also phosphorylate exogenous protein substrates. Autophosphorylation of sarcoplasmic reticulum vesicles was not stimulated by cyclic AMP, neither was it inhibited by the heat-stable protein kinase inhibitor protein. The phosphorylated membranes had the characteristics of a protein with a phosphoester bond. An average of 73 pmol Pi/mg protein were incorporated in 10 min at 30 degrees C. Addition of exogenous cyclic AMP-dependent protein kinase increased the endogenous level of phosphorylation by 25-100%. Sarcoplasmic reticulum membrane phosphorylation, mediated by either endogenous cyclic AMP-independent or exogenous cyclic AMP-dependent protein kinase, occurred on a 100 000 dalton protein and both enzyme activities resulted in enhanced calcium uptake and Ca2+-dependent ATPase (ATP phosphohydrolase, EC 3.6.1.3), in a manner similar to cardiac microsomal preparations. Regulation of Ca2+ transport in skeletal sarcoplasmic reticulum may be mediated by phosphorylation of a 100 000 dalton component of these membranes.
 ...
PMID:Phosphorylation of a 100 000 dalton component and its relationship to calcium transport in sarcoplasmic reticulum from rabbit skeletal muscle. 624 11

We have examined the possible role of adenosine 3',5'-phosphate (cAMP) in functions associated with the plasma membranes of Saccharomyces cerevisiae. Purified membranes from this source contained an adenylate cyclase which was insensitive to activation by fluoride or guanine nucleotides, only weakly responsive to changes of carbon source in the growth medium, and strongly stimulated by vanadate. They also contained at least two classes of receptor proteins for guanine nucleotides (as measured by binding of labeled 5'-guanylyl methylene diphosphate) with apparent dissociation constants equal to 1.0 x 10(-7) and 3 x 10(-6) M, a protein kinase capable of phosphorylating added histones, the activity of which was stimulated by cAMP, and cAMP receptors that may function as regulatory subunits for this kinase. Membrane proteins were also susceptible to phosphorylation by endogenous kinase(s), with polypeptides of apparent molecular weights equal to 160 x 10(3), 135 x 10(3), 114 x 10(3), and 58 x 10(3) as the major targets. Of these, the 114,000-molecular-weight polypeptide was probably identical to the proton-translocating ATPase of the membranes. However, the cAMP-dependent protein kinase did not appear to be involved in these reactions. Intact (rho+ or rho0) cells responded to dissipation of the proton electrochemical gradient across their plasma membranes by rapid and transient changes in their intracellular level of cAMP, as suggested earlier (J. M. Trevillyan and M. L. Pall, J. Bacteriol., 138:397-403, 1979). Thus, although yeast plasma membranes contain all the essential components of a stimulus-responsive adenylate cyclase system, the precise nature of the coupling device and the targets involved remain to be established.
 ...
PMID:Properties and possible functions of the adenylate cyclase in plasma membranes of Saccharomyces cerevisiae. 1458 90