Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.6.1.2 (guanylate cyclase)
 8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitric oxide (NO*) is known to exert its effects via guanylyl cyclase and cyclic GMP-dependent pathways and by cyclic GMP-independent pathways, including the posttranslational modification of proteins. Much ongoing research is focused on defining the mechanisms of NO*-mediated protein modification, the identity and function of the modified proteins, and the significance of these changes in health and disease. S-nitrosation or thionitrite formation has only been found on a limited number of residues in a subset of proteins in in vitro and in vivo studies. Protein S-nitrosation also appears to be reversible. There are several theories about the in vivo S-nitrosating agent, and most suggest a role for oxidation products of NO* in this process. Flux in cellular S-nitrosoprotein pools appears to be regulated by NO* availability and is redox-sensitive. An analysis of S-nitrosation in candidate proteins has clarified the mechanism by which NO* regulates enzymatic and cellular functions. These findings suggest the utility of using proteomic methods to identify unique targets for protein S-nitrosation to understand further the molecular mechanisms of the effects of NO*.
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PMID:Nitric oxide and posttranslational modification of the vascular proteome: S-nitrosation of reactive thiols. 1654 94

Various experimental data indicate signalling roles for nitric oxide (NO) in processes such as xylogenesis, programmed cell death, pathogen defence, flowering, stomatal closure, and gravitropism. However, it still remains unclear how NO is synthesized. Nitric oxide synthase-like activity has been measured in various plant extracts, NO can be generated from nitrite via nitrate reductase and other mechanisms of NO generation are also likely to exist. NO removal mechanisms, for example, by reaction with haemoglobins, have also been identified. NO is a gas emitted by plants, with the rate of evolution increasing under conditions such as pathogen challenge or hypoxia. However, exactly how NO evolution relates to its bioactivity in planta remains to be established. NO has both aqueous and lipid solubility, but is relatively reactive and easily oxidized to other nitrogen oxides. It reacts with superoxide to form peroxynitrite, with other cellular components such as transition metals and haem-containing proteins and with thiol groups to form S-nitrosothiols. Thus, diffusion of NO within the plant may be relatively restricted and there might exist 'NO hot-spots' depending on the sites of NO generation and the local biochemical micro-environment. Alternatively, it is possible that NO is transported as chemical precursors such as nitrite or as nitrosothiols that might function as NO reservoirs. Cellular perception of NO may occur through its reaction with biologically active molecules that could function as 'NO-sensors'. These might include either haem-containing proteins such as guanylyl cyclase which generates the second messenger cGMP or other proteins containing exposed reactive thiol groups. Protein S-nitrosylation alters protein conformation, is reversible and thus, is likely to be of biological significance.
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PMID:Nitric oxide evolution and perception. 1797 11