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A major group of G protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others.
-If you wish to design an experiment to block the G protein-coupled receptor interaction, the block would preferentially affect which of the following?
A) the exterior (cytoplasmic) end of the receptor
B) the cytosolic end of the receptor
C) the phospholipid's transmembrane domain
D) the amino acid sequence in the binding site for the G protein
E) the amino acids in the binding site for the transduction molecules

Question

Quizplus · Accepted Answer

Blocking the amino acid sequence in the binding site for the G protein would be the most effective way to prevent the G protein-coupled receptor interaction, as this is where the receptor directly interacts with the G protein. Blocking the exterior or cytosolic ends of the receptor or the transmembrane domain of the phospholipid would not have as direct an effect on the interaction. The binding site for the transduction molecules is also not directly involved in the G protein-coupled receptor interaction.

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