Structural-functional organization of signaling systems coupled to G-proteins in ameba Dictyostelium discoideum

Signaling systems sensitive to external stimuli of various nature have appeared at the earliest stages of evolution-at the level of lower eukaryotes. This review summarizes and analyzed for first time the literature data on signaling systems coupled to G-proteins the ameba Dictyostelium discoideum, one of the best studied representatives of unicellular animals. Through these systems, cAMP, chemoattractant, and polypeptide factors regulate such cellular processes as growth, movement, aggregation, differentiation, and sporulation. In Dictyostelium discoideum, heterotrimeric G-proteins were shown to play an important role in providing functional coupling between the plasma membrane receptors to enzymes-generators of second messengers, like this occurs in the higher eukaryote cells. The data are presented on comparative analysis of the primary protein structures, components of the signaling systems coupled to G-proteins in amebae and higher eukaryotes. These data indicate the high conservatism of these systems in evolution.