ISSN:
1432-1424
Keywords:
vacuole
;
lipid bilayer
;
K-channel
;
single channel
;
DIDS
;
yeast
;
Saccharomyces cerevisiae
;
Ca2+ activation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary A voltage-dependent and Ca2+-activated cation channel found in the vacuolar membrane of the yeast,Saccharomyces cerevisiae, was incorporated into planar lipid bilayer and its gating characteristics were studied at the macroscopic and single-channel levels. The open-channel probability at steady state, which was estimated by the macroscopic current measurement, gave a maximum value at −10 mV and decreased in a graded fashion as the voltage became more positive or more negative. The steady-state voltage dependence was explained by assuming two independent gates, which had different rate constants and opposite voltage dependence. The fast-responding gate opened when the voltage of thecis side (the side to which the vesicles were added) was made more negative and the slow-responding gate behaved in the opposite direction. Relatively high concentrations of Ca2+, about 1mm, were required on thecis side for opening the slow gate in a voltage-dependent manner. DIDS increased the open-channel probability of the fast gate when added to thecis side, but was ineffective on the slow gate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01871766
