Which of the following statements about α-keratins is false?
1) individual molecules are α-helical.
2) they include a major class of protein that comprises hair, fingernails and animal skin.
3) there is a strip of contiguous hydrophobic surface making a shallow spiral around the helix.
4) pairs of α-helices twist about each other in a coiled-coil structure held together entirely by hydrophobic interactions.
5) they include a small globular regions covalently linked to the surface.