Johannes E, Sanders D
Biology Department, University of York, UK.
FEBS Lett. 1995 May 22;365(1):1-6. doi: 10.1016/0014-5793(95)00424-8.
The voltage-gated Ca2+ release channel in the vacuolar membrane of sugar beet tap roots resides in two states which show similar reversal potentials in biionic conditions but differ dramatically in their single channel current and open frequency. State I has a unitary Ca2+ conductance of 3.9 +/- 0.5 pS and channel openings are rare at vacuolar resting potentials. After spontaneous and reversible transition into State II the unitary Ca2+ conductance increases three-fold, accompanied by a concomitant rise in channel activity over the physiological voltage range. The 15- to 19-fold increase in total Ca2+ current after the State I to State II transition could play an essential role in channel activation during signal transduction.
甜菜主根液泡膜上的电压门控Ca2+释放通道存在两种状态，在双离子条件下它们具有相似的反转电位，但单通道电流和开放频率却有显著差异。状态I的单位Ca2+电导为3.9±0.5 pS，在液泡静息电位时通道开放很少见。自发且可逆地转变为状态II后，单位Ca2+电导增加三倍，同时在生理电压范围内通道活性也随之增加。从状态I转变为状态II后，总Ca2+电流增加15至19倍，这可能在信号转导过程中的通道激活中起重要作用。
