Question

Discuss ionotropic and metabotropic receptor activation, noting similarities and differences in the way they function. Expand on second messenger systems, detailing the multiple downstream signaling effects. Include an example of the effect and the duration of action.

Answer 1

Ionotropic and metabotropic receptors , both are ligand gated receptors .

Ionotropic receptors opens quickly while metabotropic take a little longer depending on the steps taken to produce a response.

In ionotropic receptor , after binding of ligand there occurs a change in shape which leads to opening of the ion channel. There is no such channel in metabotropic receptors.They may or may not result in openong of ion channels somewhere else on the membranes.

They activate A GPCR which in turn will activate secondary messenger and thereafter downstream signalling .

Secondary messengers can be

1- cAMP : This leads to activation of protein kinase A which phosphorylates many protein substrates and the effect is elicited.

2- PLC - This breaks PIP2 to IP3 amd DAG . This DAG mobilise the calcium from endoplasmic reticulum .