Question

The G? subunit is associated with the plasma membrane by a covalently-attached lipid group. Of the 4 types of membrane proteins we discussed in Lecture 4, what type is G??

Answer 1

Trimeric G- proteins are also known as Guanine nucleotide binding protiens which has alpha, beta and gamma sub unit. These proteins are low molecular weight proteins and associated with inner surface of plasma membrane. When chemical signals received by receptor protein situated on plasma membrane. Now chemical signals stimulates the trimeric G- Protein which dissociated into Alpha, Beta and Gamma sub units. G- Alpha sub unit activates the enzyme adenylate cyclase which converts ATP into cyclic AMP(second messenger) in presence of Mg++ ion and catalyzes cyclase reactions.

Thus, G- protein Play important role in signal transduction pathway because it determines that chemical signal is stimulatory or inhibitory. If the signal stimulates reaction, called as agonist. if the signal is inhibitory then it is called as antagonist.

Feel free to ask for further explanation and if you have any specific doubt I can answer in comment.