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. 1996 Jan 1;107(1):19–34. doi: 10.1085/jgp.107.1.19

The kinetics of inactivation of the rod phototransduction cascade with constant Ca2+i

PMCID: PMC2219253  PMID: 8741728

Abstract

A rich variety of mechanisms govern the inactivation of the rod phototransduction cascade. These include rhodopsin phosphorylation and subsequent binding of arrestin; modulation of rhodopsin kinase by S- modulin (recoverin); regulation of G-protein and phosphodiesterase inactivation by GTPase-activating factors; and modulation of guanylyl cyclase by a high-affinity Ca(2+)-binding protein. The dependence of several of the inactivation mechanisms on Ca2+i makes it difficult to assess the contributions of these mechanisms to the recovery kinetics in situ, where Ca2+i is dynamically modulated during the photoresponse. We recorded the circulating currents of salamander rods, the inner segments of which are held in suction electrodes in Ringer's solution. We characterized the response kinetics to flashes under two conditions: when the outer segments are in Ringer's solution, and when they are in low-Ca2+ choline solutions, which we show clamp Ca2+i very near its resting level. At T = 20-22 degrees C, the recovery phases of responses to saturating flashes producing 10(2.5)-10(4.5) photoisomerizations under both conditions are characterized by a dominant time constant, tau c = 2.4 +/- 0.4 s, the value of which is not dependent on the solution bathing the outer segment and therefore not dependent on Ca2+i. We extended a successful model of activation by incorporating into it a first-order inactivation of R*, and a first-order, simultaneous inactivation of G-protein (G*) and phosphodiesterase (PDE*). We demonstrated that the inactivation kinetics of families of responses obtained with Ca2+i clamped to rest are well characterized by this model, having one of the two inactivation time constants (tau r* or tau PDE*) equal to tau c, and the other time constant equal to 0.4 +/- 0.06 s.

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Selected References

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  1. Angleson J. K., Wensel T. G. Enhancement of rod outer segment GTPase accelerating protein activity by the inhibitory subunit of cGMP phosphodiesterase. J Biol Chem. 1994 Jun 10;269(23):16290–16296. [PubMed] [Google Scholar]
  2. Arshavsky VYu, Bownds M. D. Regulation of deactivation of photoreceptor G protein by its target enzyme and cGMP. Nature. 1992 Jun 4;357(6377):416–417. doi: 10.1038/357416a0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Arshavsky V. Y., Dumke C. L., Bownds M. D. Noncatalytic cGMP-binding sites of amphibian rod cGMP phosphodiesterase control interaction with its inhibitory gamma-subunits. A putative regulatory mechanism of the rod photoresponse. J Biol Chem. 1992 Dec 5;267(34):24501–24507. [PubMed] [Google Scholar]
  4. Arshavsky V. Y., Dumke C. L., Zhu Y., Artemyev N. O., Skiba N. P., Hamm H. E., Bownds M. D. Regulation of transducin GTPase activity in bovine rod outer segments. J Biol Chem. 1994 Aug 5;269(31):19882–19887. [PubMed] [Google Scholar]
  5. Bader C. R., Macleish P. R., Schwartz E. A. A voltage-clamp study of the light response in solitary rods of the tiger salamander. J Physiol. 1979 Nov;296:1–26. doi: 10.1113/jphysiol.1979.sp012988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Baylor D. A., Hodgkin A. L., Lamb T. D. The electrical response of turtle cones to flashes and steps of light. J Physiol. 1974 Nov;242(3):685–727. doi: 10.1113/jphysiol.1974.sp010731. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Baylor D. A., Nunn B. J. Electrical properties of the light-sensitive conductance of rods of the salamander Ambystoma tigrinum. J Physiol. 1986 Feb;371:115–145. doi: 10.1113/jphysiol.1986.sp015964. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Bennett N., Sitaramayya A. Inactivation of photoexcited rhodopsin in retinal rods: the roles of rhodopsin kinase and 48-kDa protein (arrestin). Biochemistry. 1988 Mar 8;27(5):1710–1715. doi: 10.1021/bi00405a049. [DOI] [PubMed] [Google Scholar]
  9. Breton M. E., Schueller A. W., Lamb T. D., Pugh E. N., Jr Analysis of ERG a-wave amplification and kinetics in terms of the G-protein cascade of phototransduction. Invest Ophthalmol Vis Sci. 1994 Jan;35(1):295–309. [PubMed] [Google Scholar]
  10. Cobbs W. H., Pugh E. N., Jr Kinetics and components of the flash photocurrent of isolated retinal rods of the larval salamander, Ambystoma tigrinum. J Physiol. 1987 Dec;394:529–572. doi: 10.1113/jphysiol.1987.sp016884. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Dumke C. L., Arshavsky V. Y., Calvert P. D., Bownds M. D., Pugh E. N., Jr Rod outer segment structure influences the apparent kinetic parameters of cyclic GMP phosphodiesterase. J Gen Physiol. 1994 Jun;103(6):1071–1098. doi: 10.1085/jgp.103.6.1071. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Durham A. C. A survey of readily available chelators for buffering calcium ion concentrations in physiological solutions. Cell Calcium. 1983 Feb;4(1):33–46. doi: 10.1016/0143-4160(83)90047-7. [DOI] [PubMed] [Google Scholar]
  13. Fain G. L., Lamb T. D., Matthews H. R., Murphy R. L. Cytoplasmic calcium as the messenger for light adaptation in salamander rods. J Physiol. 1989 Sep;416:215–243. doi: 10.1113/jphysiol.1989.sp017757. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Gorczyca W. A., Gray-Keller M. P., Detwiler P. B., Palczewski K. Purification and physiological evaluation of a guanylate cyclase activating protein from retinal rods. Proc Natl Acad Sci U S A. 1994 Apr 26;91(9):4014–4018. doi: 10.1073/pnas.91.9.4014. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Gray-Keller M. P., Detwiler P. B. The calcium feedback signal in the phototransduction cascade of vertebrate rods. Neuron. 1994 Oct;13(4):849–861. doi: 10.1016/0896-6273(94)90251-8. [DOI] [PubMed] [Google Scholar]
  16. Hagins W. A., Penn R. D., Yoshikami S. Dark current and photocurrent in retinal rods. Biophys J. 1970 May;10(5):380–412. doi: 10.1016/S0006-3495(70)86308-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Hodgkin A. L., McNaughton P. A., Nunn B. J. Measurement of sodium-calcium exchange in salamander rods. J Physiol. 1987 Oct;391:347–370. doi: 10.1113/jphysiol.1987.sp016742. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Hodgkin A. L., McNaughton P. A., Nunn B. J. The ionic selectivity and calcium dependence of the light-sensitive pathway in toad rods. J Physiol. 1985 Jan;358:447–468. doi: 10.1113/jphysiol.1985.sp015561. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Hodgkin A. L., McNaughton P. A., Nunn B. J., Yau K. W. Effect of ions on retinal rods from Bufo marinus. J Physiol. 1984 May;350:649–680. doi: 10.1113/jphysiol.1984.sp015223. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Hodgkin A. L., Nunn B. J. Control of light-sensitive current in salamander rods. J Physiol. 1988 Sep;403:439–471. doi: 10.1113/jphysiol.1988.sp017258. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Hood D. C., Birch D. G. Rod phototransduction in retinitis pigmentosa: estimation and interpretation of parameters derived from the rod a-wave. Invest Ophthalmol Vis Sci. 1994 Jun;35(7):2948–2961. [PubMed] [Google Scholar]
  22. Kahlert M., Pepperberg D. R., Hofmann K. P. Effect of bleached rhodopsin on signal amplification in rod visual receptors. Nature. 1990 Jun 7;345(6275):537–539. doi: 10.1038/345537a0. [DOI] [PubMed] [Google Scholar]
  23. Karpen J. W., Zimmerman A. L., Stryer L., Baylor D. A. Gating kinetics of the cyclic-GMP-activated channel of retinal rods: flash photolysis and voltage-jump studies. Proc Natl Acad Sci U S A. 1988 Feb;85(4):1287–1291. doi: 10.1073/pnas.85.4.1287. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Kawamura S. Rhodopsin phosphorylation as a mechanism of cyclic GMP phosphodiesterase regulation by S-modulin. Nature. 1993 Apr 29;362(6423):855–857. doi: 10.1038/362855a0. [DOI] [PubMed] [Google Scholar]
  25. Klenchin V. A., Calvert P. D., Bownds M. D. Inhibition of rhodopsin kinase by recoverin. Further evidence for a negative feedback system in phototransduction. J Biol Chem. 1995 Jul 7;270(27):16147–16152. doi: 10.1074/jbc.270.27.16147. [DOI] [PubMed] [Google Scholar]
  26. Kraft T. W., Schneeweis D. M., Schnapf J. L. Visual transduction in human rod photoreceptors. J Physiol. 1993 May;464:747–765. doi: 10.1113/jphysiol.1993.sp019661. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Lagnado L., Baylor D. A. Calcium controls light-triggered formation of catalytically active rhodopsin. Nature. 1994 Jan 20;367(6460):273–277. doi: 10.1038/367273a0. [DOI] [PubMed] [Google Scholar]
  28. Lagnado L., Cervetto L., McNaughton P. A. Calcium homeostasis in the outer segments of retinal rods from the tiger salamander. J Physiol. 1992 Sep;455:111–142. doi: 10.1113/jphysiol.1992.sp019293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Lamb T. D., Matthews H. R. Incorporation of analogues of GTP and GDP into rod photoreceptors isolated from the tiger salamander. J Physiol. 1988 Dec;407:463–487. doi: 10.1113/jphysiol.1988.sp017426. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Lamb T. D., Pugh E. N., Jr A quantitative account of the activation steps involved in phototransduction in amphibian photoreceptors. J Physiol. 1992 Apr;449:719–758. doi: 10.1113/jphysiol.1992.sp019111. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Lamb T. D. Stochastic simulation of activation in the G-protein cascade of phototransduction. Biophys J. 1994 Oct;67(4):1439–1454. doi: 10.1016/S0006-3495(94)80617-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Matthews H. R. Effects of lowered cytoplasmic calcium concentration and light on the responses of salamander rod photoreceptors. J Physiol. 1995 Apr 15;484(Pt 2):267–286. doi: 10.1113/jphysiol.1995.sp020664. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Matthews H. R., Murphy R. L., Fain G. L., Lamb T. D. Photoreceptor light adaptation is mediated by cytoplasmic calcium concentration. Nature. 1988 Jul 7;334(6177):67–69. doi: 10.1038/334067a0. [DOI] [PubMed] [Google Scholar]
  34. Miller J. L., Korenbrot J. I. Differences in calcium homeostasis between retinal rod and cone photoreceptors revealed by the effects of voltage on the cGMP-gated conductance in intact cells. J Gen Physiol. 1994 Nov;104(5):909–940. doi: 10.1085/jgp.104.5.909. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Nakatani K., Yau K. W. Calcium and light adaptation in retinal rods and cones. Nature. 1988 Jul 7;334(6177):69–71. doi: 10.1038/334069a0. [DOI] [PubMed] [Google Scholar]
  36. Nakatani K., Yau K. W. Sodium-dependent calcium extrusion and sensitivity regulation in retinal cones of the salamander. J Physiol. 1989 Feb;409:525–548. doi: 10.1113/jphysiol.1989.sp017511. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Pepperberg D. R., Cornwall M. C., Kahlert M., Hofmann K. P., Jin J., Jones G. J., Ripps H. Light-dependent delay in the falling phase of the retinal rod photoresponse. Vis Neurosci. 1992 Jan;8(1):9–18. doi: 10.1017/s0952523800006441. [DOI] [PubMed] [Google Scholar]
  38. Pepperberg D. R., Kahlert M., Krause A., Hofmann K. P. Photic modulation of a highly sensitive, near-infrared light-scattering signal recorded from intact retinal photoreceptors. Proc Natl Acad Sci U S A. 1988 Aug;85(15):5531–5535. doi: 10.1073/pnas.85.15.5531. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Pugh E. N., Jr, Lamb T. D. Amplification and kinetics of the activation steps in phototransduction. Biochim Biophys Acta. 1993 Mar 1;1141(2-3):111–149. doi: 10.1016/0005-2728(93)90038-h. [DOI] [PubMed] [Google Scholar]
  40. Ratto G. M., Payne R., Owen W. G., Tsien R. Y. The concentration of cytosolic free calcium in vertebrate rod outer segments measured with fura-2. J Neurosci. 1988 Sep;8(9):3240–3246. doi: 10.1523/JNEUROSCI.08-09-03240.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Sitaramayya A., Liebman P. A. Mechanism of ATP quench of phosphodiesterase activation in rod disc membranes. J Biol Chem. 1983 Jan 25;258(2):1205–1209. [PubMed] [Google Scholar]
  42. Tamura T., Nakatani K., Yau K. W. Calcium feedback and sensitivity regulation in primate rods. J Gen Physiol. 1991 Jul;98(1):95–130. doi: 10.1085/jgp.98.1.95. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Torre V., Matthews H. R., Lamb T. D. Role of calcium in regulating the cyclic GMP cascade of phototransduction in retinal rods. Proc Natl Acad Sci U S A. 1986 Sep;83(18):7109–7113. doi: 10.1073/pnas.83.18.7109. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Tsien R. Y. Intracellular measurements of ion activities. Annu Rev Biophys Bioeng. 1983;12:91–116. doi: 10.1146/annurev.bb.12.060183.000515. [DOI] [PubMed] [Google Scholar]
  45. Van Essen D. C., Gallant J. L. Neural mechanisms of form and motion processing in the primate visual system. Neuron. 1994 Jul;13(1):1–10. doi: 10.1016/0896-6273(94)90455-3. [DOI] [PubMed] [Google Scholar]
  46. Wilden U., Hall S. W., Kühn H. Phosphodiesterase activation by photoexcited rhodopsin is quenched when rhodopsin is phosphorylated and binds the intrinsic 48-kDa protein of rod outer segments. Proc Natl Acad Sci U S A. 1986 Mar;83(5):1174–1178. doi: 10.1073/pnas.83.5.1174. [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Yau K. W., Baylor D. A. Cyclic GMP-activated conductance of retinal photoreceptor cells. Annu Rev Neurosci. 1989;12:289–327. doi: 10.1146/annurev.ne.12.030189.001445. [DOI] [PubMed] [Google Scholar]

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