State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China.
Cells. 2021 Nov 6;10(11):3062. doi: 10.3390/cells10113062.
Orai channels belong to the calcium release-activated calcium (CRAC) channel family. Orai channels are responsible for the influx of extracellular Ca that is triggered by Ca depletion from the endoplasmic reticulum (ER); this function is essential for many types of non-excitable cells. Extensive structural and functional studies have advanced the knowledge of the molecular mechanism by which Orai channels are activated. However, the gating mechanism that allows Ca permeation through Orai channels is less well explained. Here, we reviewed and summarized the existing structural studies of Orai channels. We detailed the structural features of Orai channels, described structural comparisons of their closed and open states, and finally proposed a "push-pull" model of Ca permeation.
Orai 通道属于钙释放激活钙 (CRAC) 通道家族。Orai 通道负责细胞外 Ca 的内流，这是由内质网 (ER) 中 Ca 耗竭触发的；该功能对于许多类型的非兴奋性细胞至关重要。广泛的结构和功能研究提高了人们对 Orai 通道激活的分子机制的认识。然而，允许 Ca 通过 Orai 通道渗透的门控机制解释得还不够充分。在这里，我们回顾和总结了现有的 Orai 通道结构研究。我们详细描述了 Orai 通道的结构特征，比较了它们的关闭和开放状态的结构，并最终提出了 Ca 渗透的“推挽”模型。
