Holland, Eva-Maria and Braun, Franz-Josef and Nonnengässer, Christina and Harz, Hartmann and Hegemann, Peter (1996) Nature of rhodopsin-triggered photocurrents in Chlamydomonas .1. Kinetics and influence of divalent ions. BIOPHYSICAL JOURNAL, 70 (2). pp. 924-931. ISSN 0006-3495, 1542-0086
Full text not available from this repository.Abstract
In the green alga Chlamydomonas chlamyrhodopsin fulfills its role as a light sensor by absorbing light and activating photoreceptor channels within the eyespot area. At intense light stimuli, the photoreceptor (P) current triggers a fast and a slow flagellar current that finally leads to backward swimming (stop response). Here we report about probing the photoreceptor current directly at the eyespot. This allows the detection of the whole P current with a size of above 50 pA. The P current appears with a delay of less than 50 mu s, suggesting that rhodopsin and the P channel are closely coupled or form one ion channel complex. The Ca2+ dependence of the P current has been demonstrated with the established suction technique in a capacitive mode. The P current shows the maximum amplitude at only 300 nM Ca2+, and it gradually declines at higher Ca2+. In addition to Ca2+, the photoreceptor and the fast flagellar current can be carried by Sr2+ and Ba2+. Mg2+ is conducted less efficiently and at high concentrations blocks the photoreceptor channel. A motion analysis of the cells shows that only Ca2+ and Sr2+ can induce physiological stop responses, whereas the large Ba2+ currents cause abnormal long-lasting cell spiraling.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ALGA HAEMATOCOCCUS-PLUVIALIS; PHOTOPHOBIC RESPONSES; CALCIUM CONTROL; REINHARDTII; PHOTORECEPTOR; PHOTOTAXIS; CHROMOPHORE; SELECTIVITY; CELL |
| Subjects: | 500 Science > 540 Chemistry & allied sciences 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biochemie, Genetik und Mikrobiologie > Lehrstuhl für Biochemie I |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 14 Nov 2023 07:54 |
| Last Modified: | 14 Nov 2023 07:54 |
| URI: | https://pred.uni-regensburg.de/id/eprint/51951 |
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