In: Biology
explain the role of alpha helix and beta helix in transmembrane
In transmembrane protein alpha helix is present in the form of alpha helical and beta sheet is present in the form of Beta-barrel.
Alpha-helical is a most common form of secondary structure that is present in the membrane. In alpha helical from mostly hydrophobic residues are present. Since the membrane is also hydrophobic so these residues interact with membrane and stabilize the protein in the membrane. When hydrophilic residues are present in the alpha helix then they interact with the hydrophilic residue of the other alpha helix.
As we can see from the figure that all the hydrophobic residues are on the one side of the helix and all the hydrophobic residues are towards the opposite side of the same helix. Some of the example of alpha helix transmembrane proteins- Sodium channel.
Beta-Barrel- In case of beta-barrel all the hydrophobic residues are towards the outside of the barrel and all the hydrophilic residues are towards the inside the barrel. This barrel helps in the movement of hydrophilic molecules through it. One of the Beta-barrel protein is Porin which helps in the movement of water molecule from outside to indie the cells