Depolarization-Activated K+ Channel in Chara Droplets.
Plant Physiol
; 106(1): 313-319, 1994 Sep.
Article
en En
| MEDLINE
| ID: mdl-12232330
A novel potassium channel was characterized in the droplet membrane of Chara gymnophylla. This channel has a conductance of about 90 pS (in symmetrical 0.15 M KCl), which is lower compared to the 170-pS K+ channel predominant in this preparation. In contrast to the large conductance K+ channel, the novel channel opened with a delay at depolarization and closed at hyperpolarization and did not require cytosolic Ca2+ for its opening. It also showed comparatively weak selectivity for K+ over other monovalent cations, although its cation to anion selectivity was high. Externally or internally applied Cs+ blocked the channel in a voltage-dependent manner, similarly to the 170-pS channel. The sensitivity of the 90-pS channel to external tetraethylammonium chloride (half-blocking concentration approximately 1.5 mM) was 20-fold higher compared to the large conductance channel. With respect to its voltage-gating kinetics, the 90-pS channel was identified as a "slow delayed rectifier."
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Plant Physiol
Año:
1994
Tipo del documento:
Article
País de afiliación:
Yugoslavia
Pais de publicación:
Estados Unidos