What configures a TRANSMEMBRANE domain At least 20 ammo acid

What configures a TRANSMEMBRANE domain? At least 20 ammo acids m a row that have polar or charged side chains At least 20 amino acids in a row that have non-polar side chains a sequence of 20 polar amino acids A stretch of ammo acids intercalated by non-polar and polar ammo acids where all nonpolar ammo acids face the membrane and polar amino acids produce a hydrophilic lumen.

Solution

d. A stretch of amino acids intercalated by polar and non polar amino acids where all polar amino acids face the membrane and polar amino acids produce a hydrophilic lumen.

Explaination:

Transmembrane proteins are proteins which span through lipid bilayer of the cell membrane. They will not be stable if they have all polar or all non polar amino acids are present. As cytoplasm has water content, If the transmembrane domain consists of only polar amino acids, then they are hydrophilic and will be stable towards lumen and not in between membrane.

Hence both polar and non polar amino acids are present in transmembrane proteins. These are generally used in transportation of ions and solutes.