Definitions for "Second messenger"
Small molecule that is formed in or released into the cytosol in response to an extracellular signal and helps to relay the signal to the interior of the cell. Examples include cAMP, IP and Ca2+.
Small diffusible intracellular signalling molecule, produced as a result of receptor stimulation, that conveys the signal from the receptor to some enzyme or molecular system in the cell, which mediates the cell's response. Common second messengers are cyclic AMP, cyclic GMP, Ca2+, inositol 1,4,5-trisphosphate and 1,2-diacylglycerol.
An intracellular signaling molecule whose concentration increases (or decreases) in response to binding of an extracellular ligand to a cell-surface receptor and participates in mediating the cellular response to the ligand. Examples include cAMP, Ca2+, diacylglycerol, and inositol 1,4,5-trisphosphate.