Rod phototransduction parameter values

Range Table - link
Organism vertebrates
Reference Ramanathan S, Detwiler PB, Sengupta AM, Shraiman BI. G-protein-coupled enzyme cascades have intrinsic properties that improve signal localization and fidelity. Biophys J. 2005 May88(5):3063-71. p.3065 table 1PubMed ID15681646
Primary Source Pugh EN Jr, Lamb TD. Amplification and kinetics of the activation steps in phototransduction. Biochim Biophys Acta. 1993 Mar 1 1141(2-3):111-49. & Chen, C.-K., M. E. Burns, W. He, T. G. Wensel, D. A. Baylor, and M. I. Simon. 2000. Slowed recovery of rod photoreceptors in mice lacking the GTPase accelerating protein RGS9-1. Nature. 403: 557–560. & Kahlert, M., and K. P. Hofmann. 1991. Reaction rate and collision efficiency of the rhodopsin-transducin system in intact retinal rods. Biophys. J. 59: 375–386.& Leskov, I. B., V. A. Klenchin, J. W. Handy, G. G. Whitlock, V. I. Govardovskii, M. D. Bownds, T. D. Lamb, E. N. Pugh, Jr., and V. Y. Arshavsky. 2000. The gain of rod phototransduction: reconciliation of biochemical and electrophysiological measurements. Neuron. 27:525– 537. & Hamm, H. E., and M. D. Bownds. 1986. Protein complement of rod outer segments of frog retina. Biochemistry. 25: 4512–4523. & Dumke, C. L., V. Y. Arshavsky, P. D. Calvert, M. D. Bownds, and E. N. Pugh, Jr. 1994. Rod outer segment structure influences the apparent kinetic parameters of cyclic GMP phosphodiesterase. J. Gen. Physiol. 103: 1071–1098.PubMed ID8382952, 10676965, 1901231, 11055435, 3021191, 7931138
Comments P.3066 left column bottom paragraph:"[Investigators’] analysis has, for simplicity’s sake, ignored the diffusion of R* and E*. These additional diffusive processes are similar in effect to an increase in DG and lead to the reduction of the saturation parameter S. Yet, since [their] estimated value of S, based on Table 1 parameters, is in the range of 10–100 and thus is much larger than 1, its reduction—even by a factor of 2 or 3—would not take the system out of the S . 1 regime analyzed above. Note also that in the regime corresponding to this condition, the size of the spot and the peak amplitude of effector activity are independent of diffusivity and are determined by the balance of k1 and kH." Keywords:Rhodopsin,transducing,phosphodiesterase,rod,retina,phototransduction
Entered by Uri M
ID 110363