カルシウムイオンが阻害的に作用することによってなされる生体制御機構について

シグナル伝達と細胞機能調節

抄録

The intracellular concentration of Ca²⁺([Ca²⁺]_i) in eukaryotic cells is low under resting conditions. Membrane stimulation can produce a transient increase in [Ca²⁺]_i from submicromolar to micromolar levels. Classically, the effects of elevated [Ca²⁺]_i on eukaryotic cell responses are excitatory: they induce muscle contraction or activate metabolic systems. However, micromolar concentration of Ca²⁺ has been found to inhibit the actin-myosin-ATP interaction of the lower eukaryote Physarum polycephalum, which is the first example of an effect transiently abolished by elevation of [Ca²⁺]_i in response to extracellular stimulation (Kohama, K.: Trends Pharmacol. Sci. 22, 433-435, 1991). The inhibitory effects on the interaction are closely related to myosin phosphorylation. The activities of kinases to phosphorylate myosin was also inhibited by Ca²⁺. This article describes the inhibitory mode for Ca²⁺ regulation of the actomyosin system in Physarum and reviews this inhibitory mode discovered subsequently in many different cell types in both plants and animals.