| Two open states with progressive proton selectivities in the branched channelrhodopsin-2 photocycle. | |
| | |
MedLine Citation:
|
PMID: 20197028 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
Channelrhodopsins are light-gated ion channels that mediate vision in phototactic green algae like Chlamydomonas. In neurosciences, channelrhodopsins are widely used to light-trigger action potentials in transfected cells. All known channelrhodopsins preferentially conduct H(+). Previous studies have indicated the existence of an early and a late conducting state within the channelrhodopsin photocycle. Here, we show that for channelrhodopsin-2 expressed in Xenopus oocytes and HEK cells, the two open states have different ion selectivities that cause changes in the channelrhodopsin-2 reversal voltage during a light pulse. An enzyme kinetic algorithm was applied to convert the reversal voltages in various ionic conditions to conductance ratios for H(+) and divalent cations (Ca(2+) and/or Mg(2+)), as compared to monovalent cations (Na(+) and/or K(+)). Compared to monovalent cation conductance, the H(+) conductance, alpha, is approximately 3 x 10(6) and the divalent cation conductance, beta, is approximately 0.01 in the early conducting state. In the stationary mixture of the early and late states, alpha is larger and beta smaller, both by a factor of approximately 2. The results suggest that the ionic basis of light perception in Chlamydomonas is relatively nonspecific in the beginning of a light pulse but becomes more selective for protons during longer light exposures. |
| | |
Authors:
|
André Berndt; Matthias Prigge; Dietrich Gradmann; Peter Hegemann |
Related Documents
:
|
1751008 - Interactions between amygdaloid and hypothalamic self-stimulation: a re-examination. 10049478 - Courtship song rhythms in drosophila yakuba. 22460628 - Cuttlefish rely on both polarized light and landmarks for orientation. 22418898 - Bipolar electrochemistry for cargo-lifting in fluid channels. 21302988 - Wind-generated ambient noise in a topographically isolated basin: a pre-industrial era ... 998208 - Plethysmography as an objective method of audiometry. |
Publication Detail:
|
Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
|
Title: Biophysical journal Volume: 98 ISSN: 1542-0086 ISO Abbreviation: Biophys. J. Publication Date: 2010 Mar |
Date Detail:
|
Created Date: 2010-03-03 Completed Date: 2010-05-19 Revised Date: 2011-07-26 |
Medline Journal Info:
|
Nlm Unique ID: 0370626 Medline TA: Biophys J Country: United States |
Other Details:
|
Languages: eng Pagination: 753-61 Citation Subset: IM |
Copyright Information:
|
2010 Biophysical Society. Published by Elsevier Inc. All rights reserved. |
Affiliation:
|
Institute for Biology, Humboldt-Universität zu Berlin, Germany. |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Animals Cations, Divalent / pharmacology Cell Line Humans Ion Channel Gating / drug effects, radiation effects* Light* Models, Biological Oocytes / drug effects, metabolism, radiation effects Protons* Rhodopsin / metabolism* Xenopus / metabolism |
| Chemical | |
Reg. No./Substance:
|
0/Cations, Divalent; 0/Protons; 9009-81-8/Rhodopsin |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Harmonic oscillations in homeostatic controllers: Dynamics of the p53 regulatory system.
Next Document: Modulation of KvAP unitary conductance and gating by 1-alkanols and other surface active agents.