Principles of Intracellular Signaling in Ciliated Protozoa—A Brief Outline

Abstract

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 2+ , provided from different sources, and proteins for membrane recognition and fusion, such as SNAREs, GTPases and high affinity Ca 2+ -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.

What is Life?

“…If we focus on protozoa, single-celled eukaryotes like ciliates, we can find various signaling molecules used to coordinate interactions, such as reproduction, mating, feeding, attack, and defense (Luporini et al, 1995(Luporini et al, , 2006Jacob et al, 2015). Several classes of hormones and other secretions, such as secondary metabolites, have been identified (Plattner, 2016). Ciliates synthesize and secrete cell-type-specific proteins into their extracellular medium.…”