Decoding the Bell-Shaped Calcium Spikes in Phosphorylation Cycles of Flagella.

We investigate the messenger role of calcium ions implicated in the regulation of wave-like bending dynamics of flagella. The emphasis is on microtubules of flagellar axoneme serving as nonlinear transmission lines for bell-shaped spikes of calcium ions. The calcium sensitive proteins, such as calmodulin, exhibit activation dependence on the spike train frequency and amplitude. Here, we analyze a Ca decoding module IDA-I1 whose activity is controlled by Ca activated kinase. We find that trains of Ca spikes are advantageous compared to a constant rise in Ca concentration as being more efficient and much less prone to noisy fluctuations.