Ca2+ signaling in polarized exocrine cells.

Abstract

Exocrine cells respond to a battery of neurotransmitters and hormones that act on G protein-coupled and G protein-independent receptors. Receptors transmit their signals by activation of biochemical pathways that change the concentration of second messengers, the most common of which are cAMP and intracellular Ca2+ ions ([Ca2+] i ). Many G protein-coupled receptors (GPCR) expressed in a given cell, activate the same biochemical pathway changing the concentration of the same second messengers. With the development of techniques that measure the concentration of second messengers in single cells and subcellular compartments, it became clear that different receptors using the same biochemical pathway could generate receptor-specific signals. In this short review, we summarize the current knowledge regarding a central question in cell signaling (Hunter, 2000: Weng et al., 1999) of how signaling specificity is achieved by GPCR expressed in a given cell using the same signaling pathway.