Purchase this article with an account.
Hakim Muradov, Nikolai O. Artemyev; Transducin-dependent Activation Of PDE6 Is Influenced By The Type Of Its Inhibitory P-subunit. Invest. Ophthalmol. Vis. Sci. 2011;52(14):48.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Cone phosphodiesterase-6 (PDE6) is activated by transducin in solution much more potently than rod PDE6. This difference may originate from the dissimilar cGMP-binding properties of the rod and cone PDE6 regulatory GAF domains and/or from the presence of homologous yet distinct inhibitory γ-subunits (Pγ). The aim of this study was to examine potential contribution of cone- and rod-specific Pγ-subunits to the difference in transducin-dependent activation of PDE6.
Bovine rod PDE6 containing recombinant rod or cone Pγ-subunits were obtained through exchange of the purified Pγ-subunits for endogenous Pγ. Likewise, PDE6 containing chimeric rod/cone Pγ subunits were obtained. The reconstituted PDE6 enzymes were analyzed for activation with the GTPγS-bound rod- or cone-specific transducin-a subunits.
The replacement of rod Pγ with cone Pγ in bovine rod PDE6 markedly decreased the concentrations of rod and cone transducins required for half-maximal activation of the enzyme and increased the maximal activation level. A similar replacement using rod Pγ had little effect. Experiments are underway to identify cone Pγ determinants responsible for the facilitation of PDE6 activation and to determine the effect of Pγ replacement on activation of cone PDE6 by transducin.
Our results suggest that the difference in rod and cone PDE6 activation by transducin may at least in part be attributed to the cell-type specific Pγ subunit.
This PDF is available to Subscribers Only