Principles of Intracellular Signaling in Ciliated Protozoa : A Brief Outline

Ciliates have available most of the intracellular signaling mechanisms known from metazoans. Long-range signals are represented by firmly installed microtubules serving as gliding rails aiming at specific targets. Many components are distinctly arranged to guarantee locally restricted effects. Short-range signals include Ca, provided from different sources, and proteins for membrane recognition and fusion, such as SNAREs, GTPases and high affinity Ca-binding proteins (still to be defined). A battery of ion conductances serves for electric coupling from the outside medium to specific responses, notably ciliary activity, which also underlies gravitaxis responses. Eventually cyclic nucleotides are involved, e.g. in ciliary signaling. Furthermore, an elaborate system of protein kinases and phosphatases exerts signaling mechanisms in widely different processes. 2.