The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Phosphodiesterase activation by photoexcited rhodopsin is quenched when rhodopsin is phosphorylated and binds the intrinsic 48-kDa protein of rod outer segments.

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). Subsequent deactivation of this light-activated enzyme cascade involves hydrolysis of the GTP bound to transducin, as well as decay of the activating capacity of R*. We report here that deactivation of PDEase in rod outer segment suspensions is highly enhanced by addition of ATP and purified 48-kDa protein, which is an intrinsic rod outer segment protein that is soluble in the dark but binds to photolyzed rhodopsin that has been phosphorylated by rhodopsin kinase and ATP [Kühn, H., Hall, S.W. & Wilden, U. (1984) FEBS Lett. 176, 473-478]. To analyze the mechanism by which ATP and 48-kDa protein deactivate PDEase, we used an ATP-free system consisting of thoroughly washed disk membranes, whose rhodopsin had been previously phosphorylated and chromophore-regenerated, and to which purified PDEase and transducin were reassociated. Such phosphorylated membranes exhibited a significantly lower (by a factor less than or equal to 5) light-induced PDEase-activating capacity than unphosphorylated controls. 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. Addition of ATP had little further effect. 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. Our data suggest that 48-kDa protein binds to phosphorylated R* and thereby quenches its capacity to activate transducin and PDEase.[1]


WikiGenes - Universities