PerspectiveCell Biology

How to STIMulate Calcium Channels

Science  01 Oct 2010:
Vol. 330, Issue 6000, pp. 43-44
DOI: 10.1126/science.1196348

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Summary

The movement of calcium across cell membranes regulates many important physiological processes in vertebrates, as various as the contraction of heart muscle, the firing of brain cells, the expression of genes by immune cells, and the secretion of hormones. Cells have two main types of calcium channels that enable calcium ions (Ca2+) to flow into the cell. Voltage-gated Ca2+ channels typically function only in electrically excitable cells, such as neurons, heart muscle cells, and insulin-producing cells in the pancreas. By contrast, store-operated Ca2+ channels work only in electrically inexcitable cells, such as lymphocytes and other cells of the immune system. Researchers have long puzzled over this pattern, in part because biochemical evidence suggested that both channel types are present in both excitable and in excitable cells. On pages 101 and 105 of this issue, reports by Park et al. and Wang et al. (1, 2) help solve the puzzle by presenting a new mechanism that determines which type of Ca2+ channel predominates in a particular cell type. These two groups show that the protein STIM1, which was already known to activate store-operated Ca2+ channels, inhibits voltage-gated Ca2+ channels. Together, the reports help to illuminate a reciprocal calcium control mechanism that, if it goes wrong, can have life-threatening consequences.