Serbian Academy of Science and Arts, Belgrade, Serbia.
Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
Eur Biophys J. 2023 Nov;52(8):705-720. doi: 10.1007/s00249-023-01685-6. Epub 2023 Oct 18.
We have considered the realistic mechanism of rapid Ca (calcium ion) buffering within the wave of calcium ions progressing along the flagellar axoneme. This buffering is an essential part of the Ca signaling pathway aimed at controlling the bending dynamics of flagella. It is primarily achieved by the mobile region of calmodulin molecules and by stationary calaxin, as well as by the part of calmodulin bound to calcium/calmodulin-dependent kinase II and kinase C. We derived and elaborated a model of Ca diffusion within a signaling wave in the presence of these molecules which rapidly buffer Ca. This approach has led to a single nonlinear transport equation for the Ca wave that contains the effects brought about by both as necessary buffers for signaling. The presence of mobile buffer calmodulin gives rise to a transport equation that is not strictly diffusive but also exhibits a sink-like effect. We solved straightforwardly the final transport equation in an analytical framework and obtained the implied function of calcium concentration. The effective diffusion coefficient depends on local Ca concentration. It is plausible that these buffers' presence can impact Ca wave speed and shape, which are essential for decoding Ca signaling in flagella. We present the solution of the transport equation for a few specified cases with physiologically reasonable sets of parameters involved.
我们考虑了钙离子波中快速钙离子缓冲的实际机制，钙离子波沿着鞭毛轴突传播。这种缓冲是钙信号通路的一个重要组成部分，旨在控制鞭毛的弯曲动力学。它主要通过钙调蛋白分子的可移动区域和固定的钙调蛋白结合蛋白，以及与钙/钙调蛋白依赖性激酶 II 和蛋白激酶 C 结合的钙调蛋白部分来实现。我们推导出并详细阐述了一个存在这些快速缓冲钙离子的信号波内钙离子扩散模型。这种方法导致了一个单一的非线性输运方程，其中包含了两个信号缓冲所带来的影响。可移动缓冲钙调蛋白的存在导致输运方程不仅具有扩散性质，还具有汇的性质。我们在解析框架中直接求解了最终的输运方程，并得到了隐含的钙浓度函数。有效扩散系数取决于局部钙浓度。这些缓冲剂的存在可能会影响钙波的速度和形状，这对鞭毛中的钙信号解码至关重要。我们给出了几个特定情况下的输运方程解，涉及到具有生理合理性的参数集。
