Inositol Lipids and Intracellular Communication
Cells communicate with each other by means of chemical signals such as hormones and neurotransmitters. There has been a major interest in trying to unravel how cells detect these incoming signals and translate the information into the second messengers responsible for regulating many diverse physiological processes. An intracellular communication system based on the products of inositol lipid hydrolysis is central to many cellular control mech anisms. This signaling pathway is particularly responsible for altering the intracellular level of calcium, which is the major theme of this article. Initially, I shall examine how cells synthesize and hydrolyze the inositol lipid responsible for generating the second messengers inositol-1,4,5-trisphosphate (Insl,4,5P3) and diacylglycerol (DG). The way in which these two messengers function to modulate calcium homeostasis will be considered with particular emphasis on how they might interact with each other to produce a highly integrated signaling network. One consequence of such interactions is that the second messengers may oscillate at variable frequencies, which may be an important element in how they mediate their effects. Before considering these more dynamic aspects, it is necessary first to describe some basic biochemical features of this inositol lipid-signaling pathway.
KeywordsEndoplasmic Reticulum Phosphatidic Acid Calcium Entry Inositol Trisphosphate External Calcium
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