calcium Signaling: Up, Down, Up, Down …What's the Point?

摘要

The simple, ionized form of the element calcium belies its value as a key carrier of information in cells. Just over a decade ago, this messenger was first seen: Calcium-sensi- tive photoproteins and fluorescent dyes al- lowed scientists to track calcium concentra- tions in the cytoplasm of single, living cells in real time and as they responded to outside cues (1). In neurons and other excitable cels, where calcium channels are opened by membrane depolarization, it was not supris- ing that intracellular calcium concentra- tions rose and fell along with the cyclical depolarizations associated with action po- tentials.