Molecular evolution of K+ channels in primitive eukaryotes.

摘要: Cnidarians and ciliate protozoans represent evolutionary interesting phylogenetic groups for the study of K+ channel evolution. Cnidaria is a primitive metazoan phylum consisting simple diploblast organisms which have few tissue types such as jellyfish, hydra, sea anemones, corals. Their divergence from rest line may predate radiation major triploblast phyla by several hundred million years (Morris, 1993). are most metazoans to an organized nervous system. Thus, comparing channels cloned cnidarians those more advanced reveal fundamental electrical excitability in In contrast, Paramecium not been designed send signals between cells, but simply control behavior, avoidance reaction, single cell. Hence, other eukaryotes, specialized neuronal signaling. Potassium involved diversity tasks universally present eukaryotes. set resting membrane potentials protozoan cells components activity virtually all eukaryotic systems. These shape, duration frequency action known participate protozoans, fungi plants well (Hille, 1992). Voltage-clamp recordings shown that various assortment voltage-gated Ca(2+)-activated widespread eukaryotes appear be crucial behavioral responses classes including locomotion rapid growth cell shape changes plants. far greatest metazoans, made strong commitment electrically excitable cellular networks. There apparent need great subtypes these metazoans. Over 50 sequences many distinct gene families reported so far, two (both plants) found The complex needs integration neuromuscular transmission triploblasts require exquisite excitability. This large part achieved extensive diverse channels.(ABSTRACT TRUNCATED AT 250 WORDS)