Question

Define the term second messenger. Briefly describe the role of cAMP or Ca^2+ in a specific signaling pathway.

Answer 1

Second messenger are small molecules inside the cytoplasm, that get activated when primary receptor bind with receptor present on the surface of the cell. They are involved in intracellular signalling. For example, cyclic AMP is involved in G protein coupled signal transduction pathway. In thIs signal transduction pathway, when G protein attach to their receptors, it activate the enzyme called adenyl cyclase which catalyze the converstion of ATP into cyclic AMP. This second messager cyclic AMP activate enzyme protein kinase A. This enzyme in turn activate many kinase protein in signal transduction pathway.