Question

Which is common feature shared between the GG-subunit of a G-protein complex and the c-ras protein?

Select one:

a. intrinsic GTPase activity

b. membrane associated protein

c. signal transduction

d. All of these

e. None of these.

Answer 1

Ans: As peripheral membrane proteins, G proteins interact with the inner side of the plasma membrane and form part of the signaling cascade activated by G protein-coupled receptors (GPCR). They are comprised of three subunits Gα, Gβ and Gγ, which are often closely associated with the intracellular domains of GPCRs.

The Ras proteins act as membrane-associated molecular switches in the early steps of signal transduction pathways associated with cell growth or differentiation. Ras shuttles between a GDP (inactive) and a GTP (active) bound state. When bound to GTP, it interacts with a variety of effectors.

These both proteins has an active role in signal transduction.

Ras has an intrinsic GTPase activity, which means that the protein on its own will hydrolyze a bound GTP molecule into GDP.

The α-subunit of G protein is the unique protein in the trimer. It possesses sites for interaction with cell membrane receptors, β,γ-subunit, intrinsic GTPase activity, and ADP ribosylation.

Hence from all the literature we can say that all of these features are shared by these two proteins.

So option D is correct.