10. Describe a trimeric G-protein. What are the subunits? How do G-proteins turn on? Nashik, India How do G-proteins turn oll? Why are they called "G" proteins?
Answers
Explanation:
Trimeric G Proteins are usually found coupled to a receptor protein and attached to the cytoplasmic face of the plasma membrane. It's function is to couple the receptor molecule to either an ion channel or enzyme (target signal Protein) where it acts as a relay Protein [1]. Trimeric G Proteins are composed of three sub-units, alpha beta and gamma. In its inactive state the alpha sub-unit is bound to GDP, when the coupled receptor is activated this alpha sub-unit releases this GDP molecule. A GTP molecule takes the place of the GDP on the alpha sub-unit and the protein under goes a large conformational change; the G protein is now in it's activated state. The sub-units dissociate into an alpha sub-unit and a beta-gamma complex which then go on to activate their target molecules which may be enzymes, this therefore carries the signal forward and the result is a cell response ....