Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new GTP-binding protein, which serves as a substrate for pertussis toxin, was prepared from porcine brain. The new G protein was separated from other GTP-binding proteins, Gi and Go, by an anion-exchange column chromatography. The mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the alpha subunit of the new G protein was between those of alpha subunits of Gi and Go. Evidence that the alpha subunit is not a proteolytic fragment of the alpha subunit is not a proteolytic fragment of the alpha subunit of Gi or Go was provided by experiments involving partial hydrolysis of these G proteins with thermolysin and their interaction with an antibody raised against the amino terminal peptide of the alpha subunit of Gi. In addition, the gamma subunit of the new G protein was indicated to be different from the gamma subunits of Gi and Go, because the latter were found to be phosphorylated by protein kinase C but the former was not. GTP-sensitive high affinity binding of muscarinic receptors with acetylcholine was observed when muscarinic receptors purified from porcine cerebrum were reconstituted in phospholipid vesicles with the new G protein as well as with Gi or Go. The proportion of the high affinity sites increased with the concentrations of the G proteins, the potency of the new G protein being similar to that of Gi but a little lower than that of Go. This GTP-sensitive high affinity binding was not observed when each G protein was pretreated with pertussis toxin and then reconstituted with muscarinic receptors. Acetylcholine accelerated the dissociation of [3H]GDP from the new G protein as well as from Gi and Go, which were reconstituted with muscarinic receptors. These results indicate that muscarinic receptors interact with at least the above three kinds of G proteins, in a pertussis toxin-sensitive manner.
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PMID:Cerebral muscarinic acetylcholine receptors interact with three kinds of GTP-binding proteins in a reconstitution system of purified components. 249 27

Thymus myosin, light chains and a synthetic peptide (S-S-K-R-A-K-A-K-T-T-K-K-R-P-Q-R-A-T-S-N-V-F-S) corresponding to the N-terminal sequence of smooth muscle myosin light chains were compared as substrates for calcium/calmodulin-dependent protein kinase (MLCK), calcium/phospholipid-dependent protein kinase (PKC), and a MgATP-activated protein kinase (H4PK) from lymphoid cells. All protein kinases catalyzed phosphorylation of the substrates although H4PK showed higher affinity for isolated light chains and the peptide. Phosphoamino acid analysis and analysis of thermolysin peptides established that PKC catalyzed phosphorylation of threonine-9 or 10. In addition, PKC and H4PK catalyzed phosphorylation at serine-19, the MLCK site. Collectively the data support the hypothesis that myosin filament assembly in nonmuscle cells may be regulated by a variety of calcium-dependent and calcium-independent protein kinases.
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PMID:Nonmuscle myosin phosphorylation sites for calcium-dependent and calcium-independent protein kinases. 308 Sep 87

Most fish protamines contain two phosphorylatable sites both of which incorporate phosphate in vivo. Here we show that in two protamines (salmine A1 and clupeine Y1) the site more distant from the N-terminus (residues 20-21) is unaffected by cAMP-dependent protein kinase while it represents the main target for protein kinase C. Such a phosphorylation is typically independent of Ca2+ and phospholipids: responsiveness to these effectors however is conferred by previous fragmentation of protamine with thermolysin. These results suggest that Ca2+, phospholipid-independent phosphorylation of protamine by protein kinase C might have physiological relevance and shed light on the structural basis for the specificity of such an unique process.
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PMID:Phosphorylation of protamines by protein kinase C: involvement of sites which are phosphorylated in vivo and are not affected by cAMP-dependent protein kinase. 357 60

Postsynaptic membranes from the electric organ of Torpedo californica, rich in the nicotinic acetylcholine receptor, were shown to contain an endogenous tyrosine protein kinase. This endogenous kinase phosphorylated three major proteins with molecular masses corresponding to 50 kDa, 60 kDa, and 65 kDa. The phosphorylation of these three proteins occurred exclusively on tyrosine residues under the experimental conditions used and was abolished by 0.1% Nonidet P-40 and stimulated by Mn2+. The 50-kDa, and 60-kDa, and 65-kDa phosphoproteins were demonstrated to be the beta, gamma, and delta subunits, respectively, of the nicotinic acetylcholine receptor by purification of the phosphorylated receptor using affinity chromatography. The endogenous tyrosine kinase specifically phosphorylated the beta, gamma, and delta subunits rapidly to a final stoichiometry of approximately equal to 0.5 mol of phosphate per mol of sub-unit. Two-dimensional phosphopeptide mapping of the phosphorylated beta, gamma, and delta subunits, after limit proteolysis with trypsin or thermolysin, indicated that each subunit was phosphorylated on a single site. Locations are proposed for the amino acid residues phosphorylated on the receptor by the tyrosine-specific protein kinase and by two other protein kinases (cAMP-dependent protein kinase and protein kinase C) which phosphorylate the receptor.
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PMID:Phosphorylation of the nicotinic acetylcholine receptor by an endogenous tyrosine-specific protein kinase. 659 75

Creatine kinase (CK) was analyzed from skeletal muscle of wood frogs, Rana sylvatica, a species that survives natural whole body freezing during the winter months. Muscle CK activity increased by 35% and apparent K(m) creatine decreased by 29% when frogs froze. Immunoblotting analysis showed that this activity increase was not due to a change in total CK protein. Frog muscle CK was regulated by reversible protein phosphorylation; in vitro incubations with (32)P-ATP under conditions that facilitated the actions of various protein kinases (PKA, PKG, PKC, CaMK or AMPK) resulted in immunoprecipitation of (32)P-labeled CK. Furthermore, incubations that stimulated CaMK or AMPK altered CK kinetics. Incubation under conditions that facilitated protein phosphatases (PP2B or PP2C) reversed these effects. Phosphorylation of CK increased activity, whereas dephosphorylation decreased activity. Ion-exchange chromatography revealed that two forms of CK with different phosphorylation states were present in muscle; low versus high phosphate forms dominated in muscle of control versus frozen frogs, respectively. However, CK from control versus frozen frogs showed no differences in susceptibility to urea denaturation or sensitivity to limited proteolysis by thermolysin. The increased activity, increased substrate affinity and altered phosphorylation state of CK in skeletal muscle from frozen frogs argues for altered regulation of CK under energy stress in ischemic frozen muscle.
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PMID:Creatine kinase regulation by reversible phosphorylation in frog muscle. 1926 21