Every cell is able to communicate by sending, receiving or responding to signals in its environment. In order to trigger a physiological response, these signals must be transmitted across the cell... Show moreEvery cell is able to communicate by sending, receiving or responding to signals in its environment. In order to trigger a physiological response, these signals must be transmitted across the cell membrane. Cells have developed a complex array of mechanisms to sense changes in the extracellular environment and to transduce these changes into intracellular signals (signal transduction) that can generate a cellular response. Signal transduction can be initiated by a ligand binding to a specific receptor at the plasma membrane. These ligands (primary messengers) bind to a diverse family of receptors, such G protein-coupled receptors, tyrosine kinase receptor or serine-threonine kinase receptors. Upon ligand binding, receptors activate diverse signaling pathways giving rise to change in abundance of intracellular signaling molecules, called second messengers. One important group of second messengers is the phosphoinositide family. Show less