Parys J B, Bezprozvanny I
Laboratorium voor Fysiologie, K.U. Leuven, Belgium.
Cell Calcium. 1995 Nov;18(5):353-63. doi: 10.1016/0143-4160(95)90051-9.
Xenopus laevis oocytes (stages V and VI) are a widely used model system for the study of Ca2+ signaling. The properties of the Xenopus oocyte InsP3 receptor (InsP3R) are of paramount importance for our thinking about this system and for our efforts to model Ca2+ dynamics in the oocyte cytosol. The recent data regarding the molecular structure, the regulation and the functional properties of the Xenopus oocyte InsP3R are summarized in this review. The main properties of the Xenopus oocyte InsP3R are compared with the properties of the cerebellar InsP3R and are shown to be remarkably similar. The density of the InsP3R in Xenopus oocyte cytoplasm is estimated to a value between 1.1-4.1 x 10(14) tetrameric InsP3R/l. The use of these numbers in a quantitative model of Ca2+ wave propagation leads to values of Ca2+ wave amplitude (0.8-1.5 microM Ca2+) and velocity of the wave propagation (12-24 microns/s) that are in excellent agreement with the values observed experimentally. The density of InsP3Rs in Purkinje cells of the cerebellum is estimated to be about 20,000-fold higher, but in other types of neurons and in peripheral tissues the InsP3R density is estimated to be of the same order of magnitude as, or up to 20-fold higher than, in Xenopus oocytes. The implications of differences in InsP3R density for Ca2+ signaling are discussed.
非洲爪蟾卵母细胞（V期和VI期）是研究Ca2+信号传导广泛使用的模型系统。非洲爪蟾卵母细胞肌醇三磷酸受体（InsP3R）的特性对于我们理解这个系统以及模拟卵母细胞胞质溶胶中Ca2+动态变化的努力至关重要。本综述总结了关于非洲爪蟾卵母细胞InsP3R分子结构、调节和功能特性的最新数据。将非洲爪蟾卵母细胞InsP3R的主要特性与小脑InsP3R的特性进行了比较，结果显示它们非常相似。非洲爪蟾卵母细胞细胞质中InsP3R的密度估计为1.1 - 4.1×10(14) 四聚体InsP3R/升。在Ca2+波传播的定量模型中使用这些数值，得出的Ca2+波振幅值（0.8 - 1.5微摩尔/升Ca2+）和波传播速度值（12 - 24微米/秒）与实验观察值非常吻合。小脑浦肯野细胞中InsP3R的密度估计要高约20,000倍，但在其他类型的神经元和外周组织中，InsP3R密度估计与非洲爪蟾卵母细胞中的密度处于相同数量级，或比其高20倍。讨论了InsP3R密度差异对Ca2+信号传导的影响。
