It is called an analogous structure, because they both have the same uses.
Answer:
Protein A can be a cytoplasmic and protein B can be a membrane protein.
Explanation:
The polar amino acid will have the hydrophilic side chain so they provide the hydrophilic nature to protein and thats why usually found on outer surface of water souluble proteins.
Cytoplasm is 80% water, so these proteins usually found in cytoplasm.
The non-polar amino acid will have the hydrophobic side chain and thus provide hydrophobic nature to protein and usually found in interior portion of membrane protein.
Plasma membrane is made up of hydrophobic lipids bilayer, so these proteins are usually found in plasma membrane.
How old they are and how big they are.
