Question

Both rhodopsin in vision and the muscarinic acetylcholine receptor system in cardiac muscle are coupled to ion channels via G proteins. Describe at least two similarities and two differences between these two systems.

Answer 1

Similarities of the rhodopsin and the muscarinic acetylcholine receptor system in cardiac muscle

• G proteins are coupled with the receptor in both systems
• The ligand binds to the specific receptor in both system and activates the system

Differences between the rhodopsin and the muscarinic acetylcholine receptor system incardiac muscle are:

• In acetylcholine system, the subunit is binds to effector protein to get activate. In the rhodopsin system, there is no analogue in the system is present to the activation of subunit.
• In the acetyl choline system binding of acetylcholine opens the  K channels. In the rhodopsin system, the absorption of photons takes place and results  the closing of ion channels of Ca and Na.
• Conformational change of the receptor after activation takes place in only in rhodopsin system not in the acetylcholine system.

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