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Molecule Parameter List for GTP

The statistics table lists the distribution of a molecule acting either as a substrate, product, enzyme or as a molecule within the network.
The text color of a molecule is highlighted by color.
Statistics
GTP participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1001000

Accession and Pathway Details
Accession NameAccession No.Accession TypePathway Link
cGMP_regulation34Network
Shared_Object_cGMP_regulation GC PDE 
Though Corbin JD. et al. Eur J Biochem. (2000) 267(9):2760-7 has been mentioned in the citation, this model has been made with inputs from different literature sources, each of which has been mentioned in the notes sections. This model features hydrolysis of cGMP by bovine PDE, phosphorylation of PDE by bovine lung PKG, and activation of bovine lung PKG by cGMP binding. These mechanisms are known to be involved in cGMP level regulation. Rates have been used from different sources and the model has been tested based on Corbin JD. et al., since their work involved measuring the PDE phosphorylation and PDE activity.
On replicating Figures 2, 3 and 4 from their paper, there is approx 30% difference in results but the qualitative shape of the curves is very similar. This might be due to the fact that the Vmax values were used from different literature sources. This might lead to the discrepancy in the numbers in this model. The values shown in this model are near estimated physiological levels.In order to replicate the Figures more closely, we have run additional simulations with concentration terms changed so as to replicate the experimental conditions exactly.

GTP acting as a Molecule in  
cGMP_regulation Network
NameAccession NamePathway NameInitial Conc.
(uM)
Volume
(fL)
Buffered
GTPcGMP_regulation
Accession No. : 34
GC
Pathway No. : 177
100.0016667Yes

GTP acting as a Substrate for an Enzyme in  
cGMP_regulation Network
Enzyme Molecule /
Enzyme Activity
Accession NamePathway NameKm (uM)kcat (s^-1)RatioEnzyme TypeReagents
sGCtot  /
sGC_act
cGMP_regulation
Accession No. : 34
GC
Pathway No. : 177
3022.054Classical Michaelis-Menten
V = Etot.S.Kcat/Km+S
Substrate
GTP

Product
cGMP
The range of estimates found in the literature are: Km -> 40 - 150 uM (without NO) 20 - 40 uM (with NO) Vmax -> 10 - 100 nmol/mg/min (wihtout NO) 10 - 40 umol/mg/min (with NO). ----- thru personal correspondence from T. Bellamy, Wolfson Ins. for Biomedical Sciences, UK. NO increases the Vmax of sGC by 100-200 fold, and it has been proposed that this activation occurs subsequent to the binding of NO toa heme moiety on the enzyme. (Stone and Marletta,1995, Biochemistry,34:14668-14674).



Database compilation and code copyright (C) 2022, Upinder S. Bhalla and NCBS/TIFR
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