The presence of a hydrophobic amino acid at every third or fourth residue in $\alpha$-keratin results in which of the following?
A)a random placement of hydrophobic amino acids within the helix
B)a strip of hydrophobic surface area that, when combined with another monomer, results in the formation of a dimer through hydrophobic interactions
C)a strip of hydrophobic surface area that causes individual $\alpha$-keratin molecules to fold back on themselves through hydrophobic interactions
D)represents a deleterious mutation that causes the $\alpha$-keratin molecules to aggregate and form plaques
E)none of the above

Question

Quizplus · Accepted Answer

The presence of hydrophobic amino acids at every third or fourth residue in F1F1F1S1F1F1F10-keratin results in a strip of hydrophobic surface area that, when combined with another monomer, forms a dimer through hydrophobic interactions. This is characteristic of coiled-coil proteins, which contain heptad repeat sequences of hydrophobic residues every third or fourth position that interact with the complementary strip of hydrophobic residues in another coiled-coil protein to form a stable dimer.

The Presence of a Hydrophobic Amino Acid at Every Third α\alphaα

The Presence of a Hydrophobic Amino Acid at Every Third $\alpha$