what is a second messengerSolutionA group of molecules media

what is a second messenger?

Solution

A group of molecules mediate the intracellular action of many hormones is known as second messengers. The hormone acts as the first messenger and the second messengers mediate them to trigger their action intracellularly. Molecules like cyclic AMP (cAMP), cyclic GMP (cGMP), calcium ions and inositol – phospholipids acts as second messengers. The second messengers act up on enzymes and modulate the enzyme cascades.

The epinephrine is released from the adrenal glands in response to stress. Binding of epinephrine to the receptor triggers the reaction cascade by synthesis of cAMP, which further breaks down rapidly and converts glycogen to glucose – 1 – phosphate. In this signal transduction, the primary signal is the epinephrine hormone, receptor is the epnephrine receptor, tranducer is the cyclic AMP (cAMP) that acts as second messenger converts the inactive protein kinase in to active protein kinase. The active protein kinase gets phosphorylated and activates the glycogen phosphorylase and break downs the glycogen in to glucose - 1 phosphate.

The cAMP synthesized during the signal cascade break downs rapidly to provide phosphate groups for phosphorylation reactions of other enzymes in the signal cascade. The cAMP disassociates to AMP and provides the phosphate groups. This is the very important feature of the cAMP (a second messenger) in the signal transduction pathway.