Outwardly Rectifying Anionic Channel from the Plasma Membrane of the Fungus Phycomyces blakesleeanus
| Autor: | Natasa Todorovic, Marko Popović, Željko Vučinić, Miroslav Zivic |
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| Rok vydání: | 2009 |
| Předmět: |
Anions
Membrane potential Phycomyces Fungal protein Patch-Clamp Techniques Cell Membrane Analytical chemistry Depolarization Articles General Medicine Biology biology.organism_classification Microbiology Ion Channels Fungal Proteins Biochemistry Patch clamp Phycomyces blakesleeanus Selectivity Molecular Biology Ion channel |
| Zdroj: | Eukaryotic Cell. 8:1439-1448 |
| ISSN: | 1535-9786 1535-9778 |
| DOI: | 10.1128/ec.00059-09 |
| Popis: | In the present report, by using a patch clamp technique, we provide, to our knowledge, the first detailed description of an anionic channel from filamentous fungi. The characterized channel, an outwardly rectifying anionic channel (ORAC), is the most prominent feature of the cell membrane of the fungus Phycomyces blakesleeanus in the absence of energizing substrates. The unitary conductance of the channel is 11.3 ± 0.4 pS. It is characterized by a strong voltage dependence of the open-channel probability ( z δ; the gating charge is 2.1 ± 0.1), and the channel is activated by depolarization. The values of the time constants for voltage-induced activation and deactivation of 28 ± 3 ms for τ a and 39 ± 9 ms for τ d show that the ORAC is characterized by fast activation/deactivation kinetics. The ORAC shows strong selectivity for anions over cations and weak selectivity among anions, with a selectivity sequence of I − ≥ NO 3 − > Br − > Cl − > SO 4 2− = 4.8 > 4.4 > 2.2 > 1 > 0.55, which corresponds to Eisenman series 1. The channel is characterized by two open and two closed states, with dominant long open (τ o2 = 35.0 ± 3.9 ms) and long closed (τ c2 = 166 ± 28 ms) states occupying 63% ± 8% and 79% ± 3% of total open and closed times, respectively. The ORAC is insensitive to anthracene-9-carboxylic acid ( |
| Databáze: | OpenAIRE |
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