Question

A G protein has a Gα subunit that is incapable of GDP release. How will this impact the GPCR?_____

a. The α subunit will be incapable of binding to the Gβ and Gγ subunits.
b. The GPCR will be unable to bind ligand.
c. The α subunit will not dissociate from the GPCR.
d. The Gβ and Gγ subunits will not interact.
e. None of the answers is correct.

Answer 1

The α subunit of a G protein that cannot release GDP will not dissociate from the GPCR, hence impairing the G-protein-coupled receptor's signaling function.

Step-by-step explanation:

If a G protein has a Gα subunit that is incapable of GDP release, the impact on the GPCR (G-protein-coupled receptor) is that the α subunit will not dissociate from the GPCR. Normally, the binding of a signaling molecule to the GPCR causes the GDP to be exchanged for GTP on the Gα subunit, leading to the dissociation of the Gα from the Gβ and Gγ subunits and triggering a cellular response. Without the ability to release GDP and bind GTP, the Gα subunit remains bound to the GPCR, and the signaling pathway is not activated. Therefore, the correct answer to the student's question is 'c. The α subunit will not dissociate from the GPCR'.