Question

What effect would a mutant receptor lack- ing serine or threonine phosphorylation sites have on a cell

2. Even though GRB2 lacks intrinsic enzyme activity, it is an essential component of the epidermal growth factor (EGF) signaling pathway that activates MAP kinase. What is the function of GRB2?

Answer 1

1.) Effect of mutant receptor lacking serine or threonine phosphorylation sites ----- there will not be the induction of signalling Cascade, serine threonine kinase pathway is the only pathway which is an inhibitor of cell proliferation, it translates protein 53, protein 21 , and they are the cell cycle inhibitor. So in mutation --- cell proliferation will keep on going , responsible for the malignancy.

2.) It gets linked with epidermal growth factor kinase receptor and it is responsible for the activation of Ras and it's downstream kinases . It is composed of a SH2 domain , after binding with receptor there is a formation of SH3 domain , which is a binding site for SOS , SOS binds with Ras, and activates it by exchanging GDP with GTP.