The shortest $\alpha$ helix segment in a protein that will span a membrane bilayer has about _____ amino acid residues.

Question

Quizplus · Accepted Answer

A transmembrane helix is generally composed of 20-25 amino acid residues, with a typical sequence pattern of hydrophobic residues (e.g. F, L, I, V, M) at the transmembrane region and polar or charged residues at the flanking regions. Therefore, the shortest helix segment that spans a lipid bilayer should be at least 20 amino acid residues. Choice A (5) is too short to span a membrane bilayer, while choices C-E (50 to 200) are longer than the necessary length.

The Shortest α\alphaα Helix Segment in a Protein That Will Span a Membrane

The Shortest $\alpha$ Helix Segment in a Protein That Will Span a Membrane