Question

Are hydropathy plots useful for estimating the number and position of transmembrane α helices and β strands in a transmembrane protein?

1) Hydropathy plots are not useful for either α helices or β strands.
2) Hydropathy plots are useful for α helices but not for β strands.
3) Hydropathy plots are not useful for α helices but are for β strands.
4) Hydropathy plots are useful for both α helices and β strands.

Answer 1

Hydropathy plots are useful tools for predicting the presence and positioning of transmembrane α helices and β strands in proteins, by identifying hydrophobic regions that interact with the lipid bilayer of cell membranes.

Step-by-step explanation:

Hydropathy plots are indeed useful for estimating the number and position of transmembrane α helices and β strands in a transmembrane protein. By analyzing the amino acid sequence of a protein, hydropathy plots reveal regions with high hydrophobicity, indicative of transmembrane domains. Due to the hydrophobic nature of membrane interiors, transmembrane α helices typically consist of hydrophobic amino acids that enable the protein to span the lipid bilayer.

In addition to α helices, membrane proteins can also have β sheets that span the membrane. The structure of these proteins is stabilized by hydrogen bonds between amide and carbonyl groups within the polypeptide chain, with the hydrophobic R groups positioned to interact with the membrane's interior. Therefore, hydropathy plots can provide valuable insights into the structure and orientation of integral membrane proteins, delineating both α helical and β sheet regions that contribute to the protein's ability to traverse and interact with the lipid bilayer.