Following is a ribbon diagram for one type of opioid receptor, a family of proteins that bind morphine and other opioids and initiate their physiological effects. The opioid receptor consists mostly of a-helices; the receptor spans the cell membrane. Parts of the helix (R-groups in the following diagram) are adjacent to the lipid bilayer of the membrane.

Which group of amino acid residues are likely to be found in greatest proportion near the phospholipid bilayer (choose one)? Explain why.

A: Asp and Glu 

B: Lys, Arg, and His

C: Gly 

D: Pro

E: Phe, Leu. Ile, and Val 

F: Ser, Thr, Gln, and Asn

Transcribed Image Text:

TT phospholipid bilayer (membrane interior) phospholipid bilayer (membrane interior)