Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
Front Neural Circuits. 2019 Apr 3;13:21. doi: 10.3389/fncir.2019.00021. eCollection 2019.
In mammalian neurons, small conductance calcium-activated potassium channels (SK channels) are activated by calcium influx and contribute to the afterhyperpolarization (AHP) that follows action potentials. Three types of SK channel, SK1, SK2 and SK3 are recognized and encoded by separate genes that are widely expressed in overlapping distributions in the mammalian brain. Expression of the rat genes, rSK2 and rSK3 generates functional ion channels that traffic to the membrane as homomeric and heteromeric complexes. However, rSK1 is not trafficked to the plasma membrane, appears not to form functional channels, and the role of rSK1 in neurons is not clear. Here, we show that rSK1 co-assembles with rSK2. rSK1 is not trafficked to the membrane but is retained in a cytoplasmic compartment. When rSK2 is present, heteromeric rSK1-rSK2 channels are also retained in the cytosolic compartment, reducing the total SK channel content on the plasma membrane. Thus, rSK1 appears to act as chaperone for rSK2 channels and expression of rSK1 may control the level of functional SK current in rat neurons.
在哺乳动物神经元中，小电导钙激活钾通道（SK 通道）被钙内流激活，并有助于动作电位后的超极化（AHP）。三种类型的 SK 通道，SK1、SK2 和 SK3，由单独的基因编码，这些基因在哺乳动物大脑中的分布广泛且重叠。大鼠基因 rSK2 和 rSK3 的表达产生功能性离子通道，作为同型和异型复合物转运到膜上。然而，rSK1 不能转运到质膜，似乎不能形成功能性通道，rSK1 在神经元中的作用尚不清楚。在这里，我们表明 rSK1 与 rSK2 组装在一起。rSK1 不能转运到膜上，而是保留在细胞质隔室中。当 rSK2 存在时，异型 rSK1-rSK2 通道也保留在细胞质隔室中，从而减少质膜上的总 SK 通道含量。因此，rSK1 似乎作为 rSK2 通道的伴侣蛋白，rSK1 的表达可能控制大鼠神经元中功能性 SK 电流的水平。
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