Question

Give an example of a signalling pathway that uses the second messenger calcium describing the signalling pathway.

Answer 1

Second messenger are small, non-protein, water-soluble molecules or ions that transfers a signal to a cells interior in response to a singaling molecule bound by a singal receptor protein. They can spread quickly throughout the cell by diffusion. E.g. cAMP, ca+2, IP3, DAG

phosphoinositol pathway involves calcium, IP3, DAG as secondary messengers.

GPCReceptor activation leads to phospholipase C (PLC) activation, which cleaves phosphatidylinositol 4,5-bisphosphate (PIP) into IP3 and diacylglycerol (DAG). IP3 enters cytosoland then stimulates calcium release from the endoplasmic reticulum. Calcium activates protein kinase C (PKC) and allows PKC to bind with DAG. PKC then phosphorylates downstream substrates such as glycogen synthase and the calmodulin-binding protein neurogranin.