The gain of rod phototransduction: Reconcillation of biochemical and electrophysiological measurements

Ilya B. Leskov, Vadim A. Klenchin, Jason W. Handy, Gary G. Whitlock, Viktor I. Govardovskii, M. Deric Bownds, Trevor D. Lamb, Edward N Pugh Jr, Vadim Y. Arshavsky

Research output: Contribution to journalArticle

141 Citations (Scopus)

Abstract

We have resolved a central and long-standing paradox in understanding the amplification of rod phototransduction by making direct measurements of the gains of the underlying enzymatic amplifiers. We find that under optimized conditions a single photoisomerized rhodopsin activates transducin molecules and phosphodiesterase (PDE) catalytic subunits at rates of 120-150/s, much lower than indirect estimates from light-scattering experiments. Further, we measure the Michaelis constant, K(m), of the rod PDE activated by transducin to be 10 μM, at least 10-fold lower than published estimates. Thus, the gain of cGMP hydrolysis (determined by k(cat)/K(m)) is at least 10-fold higher than reported in the literature. Accordingly, our results now provide a quantitative account of the overall gain of the rod cascade in terms of directly measured factors.

Original languageEnglish (US)
Pages (from-to)525-537
Number of pages13
JournalNeuron
Volume27
Issue number3
StatePublished - 2000
Externally publishedYes

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Transducin
Light Signal Transduction
Phosphoric Diester Hydrolases
Rhodopsin
Catalytic Domain
Hydrolysis
Light

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Leskov, I. B., Klenchin, V. A., Handy, J. W., Whitlock, G. G., Govardovskii, V. I., Bownds, M. D., ... Arshavsky, V. Y. (2000). The gain of rod phototransduction: Reconcillation of biochemical and electrophysiological measurements. Neuron, 27(3), 525-537.

The gain of rod phototransduction : Reconcillation of biochemical and electrophysiological measurements. / Leskov, Ilya B.; Klenchin, Vadim A.; Handy, Jason W.; Whitlock, Gary G.; Govardovskii, Viktor I.; Bownds, M. Deric; Lamb, Trevor D.; Pugh Jr, Edward N; Arshavsky, Vadim Y.

In: Neuron, Vol. 27, No. 3, 2000, p. 525-537.

Research output: Contribution to journalArticle

Leskov, IB, Klenchin, VA, Handy, JW, Whitlock, GG, Govardovskii, VI, Bownds, MD, Lamb, TD, Pugh Jr, EN & Arshavsky, VY 2000, 'The gain of rod phototransduction: Reconcillation of biochemical and electrophysiological measurements', Neuron, vol. 27, no. 3, pp. 525-537.
Leskov IB, Klenchin VA, Handy JW, Whitlock GG, Govardovskii VI, Bownds MD et al. The gain of rod phototransduction: Reconcillation of biochemical and electrophysiological measurements. Neuron. 2000;27(3):525-537.
Leskov, Ilya B. ; Klenchin, Vadim A. ; Handy, Jason W. ; Whitlock, Gary G. ; Govardovskii, Viktor I. ; Bownds, M. Deric ; Lamb, Trevor D. ; Pugh Jr, Edward N ; Arshavsky, Vadim Y. / The gain of rod phototransduction : Reconcillation of biochemical and electrophysiological measurements. In: Neuron. 2000 ; Vol. 27, No. 3. pp. 525-537.
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