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.
|Keywords||Animals, Centrifugation, Density Gradient, Chromatography, Gel, Cyclic GMP-Dependent Protein Kinases/*chemistry/isolation & purification/*metabolism, Cyclic GMP/analogs & derivatives/pharmacology, Dimerization, Enzyme Inhibitors/pharmacology, Intestinal Mucosa/enzymology, Isoenzymes/*chemistry/isolation & purification/metabolism, Jejunum, Kinetics, Male, Mammals, Microvilli/enzymology, Molecular Weight, Rats, Rats, Wistar, Swine|
Vaandrager, A.B., Edixhoven, M.J., Bot, A.G., Kroos, M.A., Jarchau, T., Lohmann, S., … de Jonge, H.R.. (1997). Endogenous type II cGMP-dependent protein kinase exists as a dimer in membranes and can Be functionally distinguished from the type I isoforms. Journal of Biological Chemistry. Retrieved from http://hdl.handle.net/1765/8675