What characterizes the amino acids that are found in an $\alpha$-helical segment that spans a membrane?
A)exclusively circular
B)predominantly hydrophilic
C)predominantly hydrophobic
D)predominantly antiparallel
E)totally parallel

Question

Quizplus · Accepted Answer

A membrane-spanning helix would need to have a hydrophobic core facing the membrane in order to stabilize the protein in the hydrophobic environment of the membrane. Therefore, the amino acids found in this segment would be predominantly hydrophobic. The presence of the F1F1F1S1 motif suggests that the helix may be amphipathic, with a hydrophilic face on the outside of the membrane to interact with water molecules.

What Characterizes the Amino Acids That Are Found in An \alpha