Protein kinases and their therapeutic exploitation

2007 ◽  
Vol 35 (1) ◽  
pp. 7-11 ◽  
Author(s):  
L. Johnson
Keyword(s):  
Protein Kinases ◽  
Conformational Changes ◽  
Glycogen Phosphorylase ◽  
Molecular Level ◽  
Enzyme Activation ◽  
Phosphorylase Kinase ◽  
Binding Properties ◽  
Cyclin Dependent Kinases ◽  
Substrate Protein ◽  
Potential Therapeutic Application

This review focuses on the recognition properties of protein kinases at the molecular level. Phosphorylation of the substrate protein by a protein kinase can result in enzyme activation or inhibition, conformational changes that change recognition properties, or the creation of a surface with distinct binding properties. Protein kinases have become important targets for the development of inhibitors with potential therapeutic application. Various examples are considered in this review, and I discuss our own work on glycogen phosphorylase and phosphorylase kinase, and the structures of proteins involved with the cell cycle, including cyclins and cyclin-dependent kinases.

Glycogen Phosphorylase in the Fat Body of Two Cockroach Species, Periplaneta americana and Nauphoeta cinerea: Isolation, Partial Characterization of Three Forms and Activation by Hypertrehalosaemic Hormones

1991 ◽  
Vol 46 (1-2) ◽  
pp. 149-162 ◽  
Author(s):  
Gerd Gäde
Keyword(s):  
Anion Exchange ◽  
Glycogen Phosphorylase ◽  
Periplaneta Americana ◽  
Fat Body ◽  
Phosphorylase Kinase ◽  
Phosphorylase Activity ◽  
Strong Inhibitor ◽  
Nauphoeta Cinerea ◽  
Crude Extracts ◽  
Fat Bodies

The presence of endogenous phosphorylase kinase and phosphorylase phosphatase in crude extracts of fat bodies from the cockroaches Nauphoeta cinerea and Periplaneta americana is demonstrated in vitro by activation/inactivation of glycogen phosphorylase under appropriate conditions. Fractionation of fat body extracts of both cockroach species on an anion-exchange medium results in the elution of three peaks with phosphorylase activity. According to their AMP dependency these activity peaks are designated as phosphorylase b (inactive without AMP), phosphorylase ab (active without AMP, but several stimulated with AMP) and phosphorylase a (active without AMP). It is shown chromatographically that incubating crude extracts of fat bodies from both cockroaches, under conditions where the phosphorylase kinase is active, results in all phosphorylase b being converted to the ab- or a-form , whereas under conditions where the phosphorylase phosphatase is active all phophorylase a is converted to the ab- or b-form . Endogenous phosphorylase kinase of N. cinerea crude fat body extract can convert vertebrate phosphorylase b into the a-form , and, conversely, vertebrate muscle p hosphorylase kinase and phosphorylase phosphatase, respectively, are able to convert partially purified N. cinerea phosphorylase aborb and the ab- und a-form , respectively. In resting cockroaches most of the phosphorylase activity resides in the b-form and only a small fraction (10% ) in the a-form , whereas between 26% (N . cinerea) and 35% (P. americana) occurs in the ab-form . Injection of endogenous hypertrehalosaemic peptides into N. cinerea (the decapeptide Bld-HrTH ) or P. americana (the two octapeptides Pea-CAH -I and II) causes interconversion of phosphorylase; after injection, mainly (60% ) phosphorylase a is present, while 25% and 15% exists in the ab- und b-form , respectively. Purification of the three phosphorylase forms from N. cinerea is achieved by anion-exchange chromatography on DEAE-Sephacel followed by affinity chromatography on AMP-Sepharose. The final specific activities are 2.1, 6.9 and 27.2 U /mg protein for the a-, ab- und b-form . The molecular mass of the active molecules on gel filtration is between 173,000 and 177,000, and SDS gel electrophoresis reveals a subunit mass of 87,100, suggesting a homodimeric structure for all three form s. Kinetic studies show hyperbolic saturation curves for the substrates glycogen and Pi respectively, with Kᴍ-values of 0.021, 0.019 and 0.073% for glycogen and 8.3, 6.3 and 17.9 mᴍ for Pi (a-, ab- and b-form ). Phosphorylase a exhibits a more or less hyperbolic response to AMP and needs 70 |iM A M P for m axim al stim ulation. The kinetics for the ab- and b-form s are sigm oidal and maximal activities are displayed at about 3 mᴍ (half-maximum activation as calculated from Hill plots are 55 and 280 μᴍ for the ab- und b-form , respectively). Caffeine is a strong inhibitor of the b-form , but has only a slight inhibiting effect (10 -20 % ) on the ab- and a-form in the presence of AMP.

Phosphorylase activation hypersensitivity in hearts of diabetic rats

1984 ◽  
Vol 246 (2) ◽  
pp. E134-E140 ◽  
Author(s):  
T. B. Miller
Keyword(s):  
Glycogen Phosphorylase ◽  
Diabetic Rats ◽  
Phosphorylase Kinase ◽  
Insulin Deficiency ◽  
Dependent Protein Kinase ◽  
Heart Perfusion ◽  
Free Intracellular Calcium ◽  
Dependent Protein ◽  
Induced Changes ◽  
Related Increase

A hypersensitivity of glycogen phosphorylase activation by epinephrine and glucagon has been demonstrated in isolated perfused working and non-working hearts from diabetic rats. Accumulation of tissue cAMP and activation of cAMP-dependent protein kinase in response to epinephrine and glucagon were no greater and usually less in hearts of diabetic than of normal rats. Insulin deficiency was not associated with greater changes in epinephrine-induced activation of glycogen phosphorylase kinase than that observed in normal hearts. Perfusion of hearts with subphysiological concentrations of calcium (0.83 mM) partially reversed the diabetes-related hypersensitivity of phosphorylase activation by epinephrine. The phosphorylase activation hypersensitivity to epinephrine was completely reversed by adrenalectomizing diabetic rats 5 days before heart perfusion, an effect potentially caused by steroid-induced changes in cardiac calcium metabolism. These data are consistent with the hypothesis that phosphorylase activation by phosphorylase kinase is allosterically increased in the diabetic due to a diabetes-related increase in free intracellular calcium concentrations.

Proteus in the World of Proteins: Conformational Changes in Protein Kinases

2010 ◽  
Vol 343 (4) ◽  
pp. 193-206 ◽  
Author(s):  
Matthias Rabiller ◽  
Matthäus Getlik ◽  
Sabine Klüter ◽  
André Richters ◽  
Sandra Tückmantel ◽  
...  
Keyword(s):  
Protein Kinases ◽  
Conformational Changes ◽  
The World

scholarly journals The Structure Of Phosphorylase Kinase Holoenzyme At Subnanometer Resolution, Location Of The Catalytic Subunit And The Substrate Glycogen Phosphorylase

2009 ◽  
Vol 96 (3) ◽  
pp. 413a
Author(s):  
Slavica Jonic ◽  
Vasiliki Skamnaki ◽  
Nick Brown ◽  
Nicolas Bischler ◽  
Nikos Oikonomakos ◽  
...  
Keyword(s):  
Glycogen Phosphorylase ◽  
Catalytic Subunit ◽  
Phosphorylase Kinase
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