A major group of G protein-coupled receptors contains seven transmembrane a 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 cytosolic side between helices 5 and 6 is usually substantially longer than the others.
Where would you expect to find the carboxyl end?
A) at the exterior surface
B) at the cytosol surface
C) connected with the loop at H5 and H6
D) between the membrane layers
Answer: B
The coupled G protein most likely interacts with this receptor
A) at the NH3 end.
B) at the COO- end.
C) along the exterior margin.
D) along the interior margin.
E) at the loop between H5 and H6.
Answer: E
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
Answer: D