Endogenous type II cGMP-dependent protein kinase exists as a dimer in membranes and can Be functionally distinguished from the type I isoforms.
In mammalian tissues two types of cGMP-dependent protein kinase (cGK) have been identified. In contrast to the dimeric cGK I, cGK II purified from pig intestine was shown previously to behave as a monomer. However, recombinant rat cGK II was found to have hydrodynamic parameters indicative of a homodimer. Chemical cross-linking studies showed that pig cGK II in intestinal membranes has a dimeric structure as well. However, after purification, cGK II was found to be partly proteolyzed into C-terminal monomeric fragments. Phosphorylation studies in rat intestinal brush borders revealed that the potency of cGMP analogs to stimulate or inhibit native cGK II in vitro (i.e. 8-(4-chlorophenylthio)-cGMP > cGMP > beta-phenyl-1,N2-etheno-8-bromo-cGMP > beta-phenyl-1,N2-etheno-cGMP and Rp-8-(4-chlorophenylthio)-cGMPs > Rp-beta-phenyl-1, N2-etheno-8-bromo-cGMPs, respectively) correlated well with their potency to stimulate or inhibit cGK II-mediated Cl- secretion across intestinal epithelium but differed strikingly from their potency to affect cGK I activity. These data show that the N terminus of cGK II is involved in dimerization and that endogenous cGK II displays a distinct activation/inhibition profile with respect to cGMP analogs, which permits a pharmacological dissection between cGK II- and cGK I-mediated physiological processes.
Vaandrager
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Departments of Biochemistry, Cardiovascular Research Institute COEUR, Erasmus University Rotterdam, 3000 DR Rotterdam, The Netherlands.
Edixhoven
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Bot
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Kroos
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Jarchau
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Lohmann
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Genieser
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HG
de Jonge
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HR
D000818:Animals; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000201:enzymology; D007527:Isoenzymes / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D007583:Jejunum; D007700:Kinetics; D008297:Male; D008322:Mammals; D008871:Microvilli / Q000201:enzymology; D008970:Molecular Weight; D051381:Rats; D017208:Rats, Wistar; D013552:Swine
D004791:Enzyme Inhibitors; D007527:Isoenzymes; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP