The immunosuppressant drug rapamycin exerts its function on processes of protein synthesis by interfering with the activity of mTOR. Which of the following translation factors is the protein that would normally be targeted for mTOR-mediated regulation in the absence of rapamycin?

Question

Quizplus · Accepted Answer

mTOR regulates protein synthesis by phosphorylating and activating 4E-BP, which releases eIF-4E, allowing it to initiate translation.  The principal mechanism utilized in the regulation of eIF-4E activity is through its interaction with a family of binding/repressor proteins termed 4EBPs (4E-binding proteins). There are several signal transduction pathways, the activation of which leads to phosphorylation of 4EBP resulting in the release of eIF-4E. These include mTOR complexes. The mTOR protein is a kinase which is a component of 2 distinct multiprotein complexes termed mTORC1 and mTORC2. The activity of mTORC1 is sensitive to inhibition by rapamycin, whereas mTORC2 is not. Numerous growth factors activate the kinase activity of mTOR which then phosphorylates 4EBP allowing the release of eIF-4E and activation of protein synthesis.

The Immunosuppressant Drug Rapamycin Exerts Its Function on Processes of Protein