activates cGMP phosphodiesterase (PDEase)
First-pass extracted concept
cGMP phosphodiesterase
Candidate: toolkit item2 source documents9 linked claims
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Aliases
PDEase, phosphodiesterase
Evidence Snippets
Supporting Sources
Linked Claims
Deactivation of phosphodiesterase in rod outer segment suspensions is strongly enhanced by addition of ATP and purified 48-kDa protein.
Quoted textsource-backed
We report here that deactivation of PDEase in rod outer segment suspensions is highly enhanced by addition of ATP and purified 48-kDa protein
Purified 48-kDa protein further suppresses the phosphodiesterase-activating capacity of phosphorylated membranes.
Quoted textsource-backed
Addition of purified 48-kDa protein to phosphorylated membranes further suppressed their PDEase-activating capacity; suppression could be as high as 98% (as compared to unphosphorylated membranes), depending on the amount of 48-kDa protein and the flash intensity.
Phosphorylated rhodopsin-containing membranes have lower light-induced phosphodiesterase-activating capacity than unphosphorylated control membranes.
Quoted textsource-backed
Such phosphorylated membranes exhibited a significantly lower (by a factor less than or equal to 5) light-induced PDEase-activating capacity than unphosphorylated controls.
48-kDa protein does not influence phosphodiesterase activation or deactivation with unphosphorylated control membranes when rhodopsin kinase is absent, even in the presence of ATP.
Quoted textsource-backed
In contrast, PDEase activation or deactivation with unphosphorylated control membranes was not influenced by 48-kDa protein, even in the presence of ATP, provided rhodopsin kinase was absent.
The 48-kDa protein binds to phosphorylated photoexcited rhodopsin and quenches its capacity to activate transducin and phosphodiesterase.
Quoted textsource-backed
Our data suggest that 48-kDa protein binds to phosphorylated R* and thereby quenches its capacity to activate transducin and PDEase.
Photoexcited rhodopsin catalyzes GTP binding to many copies of transducin, and GTP-bound transducin activates cGMP phosphodiesterase.
Quoted textsource-backed
Each photoexcited rhodopsin (R*) molecule catalyzes binding of GTP to many copies of the guanine nucleotide-binding protein transducin, which, in its GTP-binding form, then activates cGMP phosphodiesterase (PDEase).
The amplitude of the light-scattering signal and phosphodiesterase activity show the same dependence on flash intensity and on the concentration of GTP or p[NH]ppG.
Quoted textsource-backed
The amplitude of the light-scattering signal and the activity of the phosphodiesterase are shown to present the same dependence upon the flash intensity and upon the concentration of GTP or its analog guanosine 5'-[beta, gamma--imido]triphosphate (p[NH]ppG).
The light-scattering signal is consistent with rhodopsin-catalyzed exchange of GTP for GDP on the GTP-binding protein, corresponding to formation of the activator of cGMP phosphodiesterase.
Quoted textsource-backed
All the results obtained are consistent with the above hypothesis.
High concentrations of GTP or p[NH]ppG activate phosphodiesterase in the dark and reduce the light-scattering signal, and prior incubation with p[S]pG prevents both effects.
Quoted textsource-backed
At high concentrations of GTP or p[NH]ppG the phosphodiesterase is activated in the dark and the light-scattering signal is correspondingly reduced; both effects are prevented by previous incubation with guanosine 5'-[beta-thio]diphosphate (p[S]pG).