cGMP-dependent protein kinase

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protein kinase, cGMP-dependent, type I
Crystallographic structure of the leucine zipper domain of human cGMP dependent protein kinase I beta.^[1]
Identifiers
Symbol	PRKG1
Alt. symbols	PRKGR1B, PRKG1B
Entrez	5592
HUGO	9414
OMIM	176894
RefSeq	NM_006258
UniProt	Q13976
Other data
Locus	Chr. 10 q11.2

protein kinase, cGMP-dependent, type II
Identifiers
Symbol	PRKG2
Entrez	5593
HUGO	9416
OMIM	601591
RefSeq	NM_006259
UniProt	Q13237
Other data
Locus	Chr. 4 q13.1-21.1

cGMP-dependent protein kinase or Protein Kinase G (PKG) is a serine/threonine-specific protein kinase that is activated by cGMP. It phosphorylates a number of biologically important targets and is implicated in the regulation of smooth muscle relaxation, platelet function, sperm metabolism, cell division, and nucleic acid synthesis.

Genes and proteins

PKG are serine/threonine kinases that are present in a variety of eukaryotes ranging from the unicellular organism Paramecium to humans. Two PKG genes, coding for PKG type I (PKG-I) and type II (PKG-II), have been identified in mammals. The N-terminus of PKG-I is encoded by two alternatively spliced exons that specify for the PKG-Iα and PKG-Iβ isoforms. PKG-Iβ is activated at ~10-fold higher cGMP concentrations than PKG-Iα. The PKG-I and PKG-II are homodimers of two identical subunits (~75 kDa and ~85 kDa, respectively) and share common structural features.

Each subunit is composed of three functional domains:

(1) an N-terminal domain that mediates homodimerization, suppression of the kinase activity in the absence of cGMP, and interactions with other proteins including protein substrates
(2) a regulatory domain that contains two non-identical cGMP-binding sites
(3) a kinase domain that catalyzes the phosphate transfer from ATP to the hydroxyl group of a serine/threonine side chain of the target protein

Binding of cGMP to the regulatory domain induces a conformational change which stops the inhibition of the catalytic core by the N-terminus and allows the phosphorylation of substrate proteins. Whereas PKG-I is predominantly localized in the cytoplasm, PKG-II is anchored to the plasma membrane by N-terminal myristoylation.

Tissue distribution

In general, PKG-I and PKG-II are expressed in different cell types.

PKG-I has been detected at high concentrations (above 0.1 µmol/L) in all types of smooth muscle cells (SMCs) including vascular SMCs and in platelets. Lower levels are present in vascular endothelium and cardiomyocytes. The enzyme is also expressed in fibroblasts, certain types of renal cells and leukocytes, and in specific regions of the nervous system, for example in the hippocampus, in cerebellar Purkinje cells, and in dorsal root ganglia. Neurons express either the PKG-Iα or the PKG-Iβ isoform, platelets predominantly Iβ, and both isoforms are present in smooth muscle.
PKG-II has been detected in renal cells, zona glomerulosa cells of the adrenal cortex, club cells in distal airways, intestinal mucosa, pancreatic ducts, parotid and submandibular glands, chondrocytes, and several brain nuclei, but not in cardiac and vascular myocytes.

Specifically, in smooth muscle tissue, PKG promotes the opening of calcium-activated potassium channels,^[2] leading to cell hyperpolarization and relaxation, and blocks agonist activity of phospholipase C, reducing liberation of stored calcium ions by inositol triphosphate.

Role in cancer

Cancerous colon cells stop producing PKG, which apparently limits beta-catenin thus allowing the VEGF enzyme to solicit angiogenesis.^[3]

References

↑ PDB: 3NMD; Casteel DE, Smith-Nguyen EV, Sankaran B, Roh SH, Pilz RB, Kim C (October 2010). "A crystal structure of the cyclic GMP-dependent protein kinase I{beta} dimerization/docking domain reveals molecular details of isoform-specific anchoring". J. Biol. Chem. 285 (43): 32684–8. doi:10.1074/jbc.C110.161430. PMC 2963381. PMID 20826808.
↑ Kyle BD, Hurst S, Swayze RD, Sheng J, Braun AP (Feb 2013). "Specific phosphorylation sites underlie the stimulation of a large conductance, Ca(2+)-activated K(+) channel by cGMP-dependent protein kinase". The FASEB Journal 27 (5): 2027–38. doi:10.1096/fj.12-223669. PMID 23407708.
↑ Kwon IK, Schoenlein PV, Delk J, Liu K, Thangaraju M, Dulin NO, Ganapathy V, Berger FG, Browning DD (April 2008). "Expression of cyclic guanosine monophosphate-dependent protein kinase in metastatic colon carcinoma cells blocks tumor angiogenesis". Cancer 112 (7): 1462–70. doi:10.1002/cncr.23334. PMID 18260092.

External links

EC 2.7.11.12
Cyclic GMP-Dependent Protein Kinases and the Cardiovascular System
cGMP-Dependent Protein Kinases at the US National Library of Medicine Medical Subject Headings (MeSH)

Intracellular signaling peptides and proteins

MAP

see MAP kinase pathway

Calcium

G protein

Heterotrimeric

cAMP:	Heterotrimeric G protein Gs/Gi Adenylate cyclase cAMP 3',5'-cyclic-AMP phosphodiesterase Protein kinase A

cGMP:	Transducin Guanylate cyclase cGMP 3',5'-cyclic-GMP phosphodiesterase Protein kinase G

G alpha subunit G_α GNAO1 GNAI1 GNAI2 GNAI3 GNAT1 GNAT2 GNAT3 GNAZ GNAS GNAL GNAQ GNA11 GNA12 GNA13 GNA14 GNA15/GNA16

G beta-gamma complex G_β GNB1 GNB2 GNB3 GNB4 GNB5 G_γ GNGT1 GNGT2 GNG2 GNG3 GNG4 GNG5 GNG7 GNG8 GNG10 GNG11 GNG12 GNG13 BSCL2

G protein-coupled receptor kinase AMP-activated protein kinase

Monomeric

Cyclin

Lipid

Other protein kinase

Serine/threonine:	Casein kinase 1 2 eIF-2 kinase EIF2AK3 Glycogen synthase kinase GSK1 GSK2 GSK-3 GSK3A GSK3B IκB kinase CHUK IKK2 IKBKG Interleukin-1 receptor-associated kinase IRAK1 IRAK2 IRAK3 IRAK4 Lim kinase LIMK1 LIMK2 p21-activated kinases PAK1 PAK2 PAK3 PAK4 Rho-associated protein kinase ROCK1 ROCK2 Ribosomal s6 kinase RPS6KA1

Tyrosine:	ZAP70 Focal adhesion protein-tyrosine kinase PTK2 PTK2B BTK

both	Dual-specificity kinase

Other protein phosphatase

Serine/threonine:	Protein phosphatase 2

Tyrosine:	protein tyrosine phosphatase: Receptor-like protein tyrosine phosphatase Sh2 domain-containing protein tyrosine phosphatase

both:	Dual-specificity phosphatase

Apoptosis

see apoptosis signaling pathway

GTP-binding protein regulators

see GTP-binding protein regulators

Other

see also deficiencies of intracellular signaling peptides and proteins

Kinases: Serine/threonine-specific protein kinases (EC 2.7.11-12)

Serine/threonine-specific protein kinases (EC 2.7.11.1-EC 2.7.11.20)

Non-specific serine/threonine protein kinases (EC 2.7.11.1)	LATS1 LATS2 MAST1 MAST2 STK38 STK38L CIT ROCK1 SGK SGK2 SGK3 Protein kinase B AKT1 AKT2 AKT3 Ataxia telangiectasia mutated Mammalian target of rapamycin EIF-2 kinases PKR HRI EIF2AK3 EIF2AK4 Wee1 WEE1

Pyruvate dehydrogenase kinase (EC 2.7.11.2)	PDK1 PDK2 PDK3

Dephospho-(reductase kinase) kinase (EC 2.7.11.3)	AMP-activated protein kinase α PRKAA1 PRKAA2 β PRKAB1 PRKAB2 γ PRKAG1 PRKAG2 PRKAG3

(3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)) (EC 2.7.11.4)	BCKDK BCKDHA BCKDHB

(isocitrate dehydrogenase (NADP+)) kinase (EC 2.7.11.5)	IDH2 IDH3A IDH3B IDH3G

(tyrosine 3-monooxygenase) kinase (EC 2.7.11.6)	STK4

Myosin-heavy-chain kinase (EC 2.7.11.7)	Aurora kinase Aurora A kinase Aurora B kinase

Fas-activated serine/threonine kinase (EC 2.7.11.8)	FASTK STK10

Goodpasture-antigen-binding protein kinase (EC 2.7.11.9)	-

IκB kinase (EC 2.7.11.10)	CHUK IKK2 TBK1 IKBKE IKBKG IKBKAP

cAMP-dependent protein kinase (EC 2.7.11.11)	Protein kinase A PRKACG PRKACB PRKACA PRKY

cGMP-dependent protein kinase (EC 2.7.11.12)	Protein kinase G PRKG1

Protein kinase C (EC 2.7.11.13)	Protein kinase C Protein kinase Cζ PKC alpha PRKCB1 PRKCD PRKCE PRKCH PRKCG PRKCI PRKCQ Protein kinase N1 PKN2 PKN3

Rhodopsin kinase (EC 2.7.11.14)	Rhodopsin kinase

Beta adrenergic receptor kinase (EC 2.7.11.15)	Beta adrenergic receptor kinase Beta adrenergic receptor kinase-2

G-protein coupled receptor kinases (EC 2.7.11.16)	GRK4 GRK5 GRK6

Ca2+/calmodulin-dependent (EC 2.7.11.17)	BRSK2 CAMK1 CAMK2A CAMK2B CAMK2D CAMK2G CAMK4 MLCK CASK CHEK1 CHEK2 DAPK1 DAPK2 DAPK3 STK11 MAPKAPK2 MAPKAPK3 MAPKAPK5 MARK1 MARK2 MARK3 MARK4 MELK MKNK1 MKNK2 NUAK1 NUAK2 OBSCN PASK PHKG1 PHKG2 PIM1 PIM2 PKD1 PRKD2 PRKD3 PSKH1 SNF1LK2 KIAA0999 STK40 SNF1LK SNRK SPEG TSSK2 Kalirin TRIB1 TRIB2 TRIB3 TRIO Titin DCLK1

Myosin light-chain kinase (EC 2.7.11.18)	MYLK MYLK2 MYLK3 MYLK4

Phosphorylase kinase (EC 2.7.11.19)	PHKA1 PHKA2 PHKB PHKG1 PHKG2

Elongation factor 2 kinase (EC 2.7.11.20)	EEF2K STK19

Polo kinase (EC 2.7.11.21)	PLK1 PLK2 PLK3 PLK4

Serine/threonine-specific protein kinases (EC 2.7.11.21-EC 2.7.11.30)

Polo kinase (EC 2.7.11.21)	PLK1 PLK2 PLK3 PLK4

Cyclin-dependent kinase (EC 2.7.11.22)	CDK1 CDK2 CDKL2 CDK3 CDK4 CDK5 CDKL5 CDK6 CDK7 CDK8 CDK9 CDK10 CDK12 CDC2L5 PCTK1 PCTK2 PCTK3 PFTK1 CDC2L1

(RNA-polymerase)-subunit kinase (EC 2.7.11.23)	RPS6KA5 RPS6KA4 P70S6 kinase P70-S6 Kinase 1 RPS6KB2 RPS6KA2 RPS6KA3 RPS6KA1 RPS6KC1

Mitogen-activated protein kinase (EC 2.7.11.24)	Extracellular signal-regulated MAPK1 MAPK3 MAPK4 MAPK6 MAPK7 MAPK12 MAPK15 C-Jun N-terminal MAPK8 MAPK9 MAPK10 P38 mitogen-activated protein MAPK11 MAPK13 MAPK14

MAP3K (EC 2.7.11.25)	MAP kinase kinase kinases MAP3K1 MAP3K2 MAP3K3 MAP3K4 MAP3K5 MAP3K6 MAP3K7 MAP3K8 RAFs ARAF BRAF KSR1 KSR2 MLKs MAP3K12 MAP3K13 MAP3K9 MAP3K10 MAP3K11 MAP3K7 ZAK CDC7 MAP3K14

Tau-protein kinase (EC 2.7.11.26)	TPK1 TTK GSK-3

(acetyl-CoA carboxylase) kinase (EC 2.7.11.27)	-

Tropomyosin kinase (EC 2.7.11.28)	-

Low-density-lipoprotein receptor kinase (EC 2.7.11.29)	-

Receptor protein serine/threonine kinase (EC 2.7.11.30)	Bone morphogenetic protein receptors BMPR1 BMPR1A BMPR1B BMPR2 ACVR1 ACVR1B ACVR1C ACVR2A ACVR2B ACVRL1 Anti-Müllerian hormone receptor

Dual-specificity kinases (EC 2.7.12)

MAP2K	MAP2K1 MAP2K2 MAP2K3 MAP2K4 MAP2K5 MAP2K6 MAP2K7

Proteins: enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

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