High impact information on Caged GTP

• Crystals of Ha-Ras p21 with caged GTP at the active site have been used to investigate the conformational changes of p21 on GTP hydrolysis [1].
• Complete x-ray data sets have been obtained for the starting caged-GTP state and the final GDP state after photolysis and hydrolysis, demonstrating the feasibility of time-resolved structural investigations of the process of GTP hydrolysis [2].
• The GTP binding domain of the c-Ha-ras protooncogene product (p21'c) and the corresponding region from an oncogenic mutant form of the protein in which glycine at position 12 has been replaced by valine [p21'(G12V)] have been crystallized with P3-1-(2-nitro)phenylethylguanosine 5'-O-triphosphate (caged GTP) at their active sites [2].
• X-ray crystal structure analysis of the catalytic domain of the oncogene product p21H-ras complexed with caged GTP and mant dGppNHp [3].
• The timecourse for activation of ICa by photolysis of caged-GTP was markedly altered by intracellular application of either GDP beta S or GTP gamma S. Upon maximal stimulation of ICa by intracellular dialysis with cAMP, photoreleased GTP induced a small, rapid increase in ICa followed by a gradual inhibition [4].

Biological context of Caged GTP

• In the absence of agonist, photorelease of GTP by flash photolysis of intracellularly applied caged-GTP rapidly increased the amplitude of ICa over a wide range of membrane potentials [4].

Anatomical context of Caged GTP

• Caged-GTP itself reduces the rate of microtubule assembly and oscillations at mM concentrations, consistent with a weak interaction between the nucleotide analogue and the protein [5].
• Flash photolysis of intracellular caged GTP gamma S increases L-type Ca2+ currents in cardiac myocytes [6].

Associations of Caged GTP with other chemical compounds

• The use of pure diastereomers of caged GTP complexed to the more stable p21(G12P)' mutant of p21 and the addition of n-octyl-beta-D-glucopyranoside improved the reproducibility and decreased the mosaicity of the crystals significantly [7].
• Rapid release of photolabile guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), tetralithium salt, by flash photolysis of intracellular caged-GTP gamma S increased the magnitude of the L-type calcium current: an effect independent of the ultraviolet flash per se or the production of photolytic by-products [6].

Gene context of Caged GTP

• Using caged GTP the intrinsic and GAP catalyzed GTPase activity of H-ras p21 is studied [8].

Analytical, diagnostic and therapeutic context of Caged GTP

• A lag period was also observed when ICa was stimulated by flash photolysis of caged GTP gamma S and when adenylyl cyclase was activated directly by rapid perfusion with forskolin [9].
• As an example of such investigations, the time-resolved FTIR studies on the GTPase reaction of H-ras p21 using caged GTP is presented [10].

References