Dynamic regulation of intracellular calcium signals through calcium release channels.
After the seminal work of Ebashi and coworkers which established the essential role of the intracellular Ca2+ concentration ([Ca2+]i) in the regulation of skeletal muscle contraction, we have witnessed an explosive elongation of the list of cell functions that are controlled by the [Ca2+]i. In numerous instances, release of intracellular Ca2+ stores plays important roles in Ca2+ signalling which displays significant variation in spatio-temporal pattern. There are two families of Ca2+ release channels, ryanodine receptors and inositol 1,4,5-trisphosphate (IP3) receptors. These Ca2+ release channels are structurally and functionally similar. In particular, the activity of both types of channels is regulated by the [Ca2+]i. The [Ca2+]i dependence of the Ca2+ release channel activity provides both types of channels with properties of a Ca2+ signal amplifier. This function of the ryanodine receptor is important in striated muscle excitation-contraction coupling, whereas that of the IP3 receptor seems to be the basis of the generation of Ca2+ waves. Thus the wide variety of Ca2+ signalling patterns seem to be critically dependent on the [Ca2+]i dependence of the Ca2+ release channels.
Iino
M
M
Department of Pharmacology, Faculty of Medicine, The University of Tokyo, Japan.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D008564:Membrane Potentials; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction
D015220:Calcium Channels; D002118:Calcium