Decoding Ca2+ signals:: a question of timing

Receptor-stimulated Ca2+ signals come in several flavors. The Ca2+ signals can be decoded linearly or by integration of the response. How the duration of the signal conveyed by cytosolic Ca2+ concentration ([Ca2+](i)) changes is regulated is not well understood. Liu et al. (Liu, Q., S. A. Walker, D. Gao, J. A. Taylor, Y.-F. Dai, R. S. Arkell, M. D. Bootman, H. L. Roderick, P. J. Cullen, and P. J. Lockyer. 2005. J. Cell Biol. 170: 183-190) now report an example of decoding based on the differential regulation of Ras function by two Ca2+-sensitive Ras inhibitors: Ca2+-promoted Ras activator (CAPRI), which extends the duration of the effect of Ca2+ on Ras activity, and Ras GTPase activating-like protein (RASAL), which functions as a linear decoder of the Ca2+ signal.