Cyclic GMP-dependent protein kinase

Activated PKG phosphorylates specific protein substrates on Ser or Thr residues  

Phosphorylation of specific protein substrates results in a conformational change of the phosphoproteins associated with a change in ligand binding and/or catalytic properties. Thus PKG has an important role in regulation of vascular smooth muscle, PKG-catalysed phosphorylation of specific proteins resulting in smooth muscle relaxation, vascular dilation and increased blood flow (see Chapter 7). 

A family of homologous protein kinase C isoenzymes (e.g. PKC-a, (3, y, 8, and T ) are variously activated by Ca2+, phospholipids (notably phosphatidylserine) and diacylglycerol (DAG). The inactive PKC is autoinhibited by an inhibitory domain and binding of the activating ligands changes the conformation of the autoinhibitory domain in a subtle way that overcomes the inhibition. 

Protein kinase C isozymes are activated by Euphorbiaceae plant-derived phorbol esters such as tetradecanoylphorbolacetate (TPA) that bind to the DAG-activation site. PKC can phosphorylate specific TFs that bind to DNA regulatory promoters called TPA response elements (TREs). This interaction enables transcription of specific genes. This process can be summarized as follows signalling giving elevated Ca2+ — PKC activation — TF phosphorylation — P-TF binding to TRE — specific gene transcription switched on — specific gene expression. 

A Ca2+-CaM-dependent PK with a very specific protein substrate is myosin light chain kinase (MLCK) that phosphorylates myosin light chains (MLCs) associated with the head  

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CREB stands for cyclic-AMP response element (CRE) binding protein and is a transcription factor. When phosphorylated by cyclic AMP- and cyclic GMP-dependent Protein Kinases or other protein kinases it binds to gene promoters that contain a specific binding site. After binding, the respective transcription activity is modulated. 

Cyclic nucleotides (cAMP and cGMP) are formed enzymatically from the corresponding triphosphates. As ubiquitous second messengers, they mediate many cellular functions which are initiated by first (extracellular) messengers. Their prime targets in eucaryotic cells are protein kinases ( cyclic AMP-dependent protein kinase, cyclic GMP-dependent protein kinase), ion channels and ensymes. 

Cyclic-AMP Response Element Binding Protein Cyclic GMP-dependent Protein Kinase Cyclic GMP-regulated Phosphodiesterases Cyclic Guanosine Monophosphate (Cyclic GMP cGMP)... 

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Sauzeau, V., Le Jeune, H., Cario-Toumaniantz, C, Smolensk , A., Lohmann, S.M., Bertoglio, J., Chardin, P., Pacaud, P., and Loirand, G. (2000). Cyclic GMP-dependent protein kinase signaling pathway inhibits RhoA-induced Ca2- - sensitization of contraction in vascular smooth muscle. 7 Bio/ Chem 275 21722-21729. 

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Cyclic GMP-dependent protein kinase signaling pathway inhibits RhoA-induced Ca + sensitization of contraction in vascular 45. smooth muscle. J. Biol. Chem. 2000 275 21722-21729. 

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Several markers for adult Purkinje cells have been used to trace back their origin. Wassef and Sotelo (1984) studied the expression of cyclic GMP-dependent protein kinase (cGK) immunoreactivity during development of the rat (Fig. 155). They found a transient heterogeneity of the Purkinje cells for an antibody against cyclic GMP-dependent... 

Wassef M, Sotelo C (1984) Asynchrony in the expression of cyclic GMP dependent protein kinase by clusters of Purkinje cells during the perinatal development of rat cerebellum. Neuroscience, 13, 1219-1243. 

TABLE II Properties of Cyclic GMP-Dependent Protein Kinases... 

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