Transmembrane Protein Problem?

Question

A transmembrane protein has 1000 aa. The 5th aa is found on the external side of the cell membrane. It interacts with the aqueous environment outside the cell. Amino acid 90 is inside the membrane bilayer. Aa 100-600 are intracellular, and 200-400 make a tight ball with minimal exposure to the aqueous cytoplasm. Amino acid 979 is found on the extracellular side of the protein where it forms a weak ionic bond with Cl-.a. Can you draw the protein and mark positions of all mentioned aa in it?b. What are the properties of these amino acids?----------I dont necessarily want/need the exact answers to these questions, rather i would like some guidance in what principles i would need to understand and conceptualize to attack this problem. Thanks all !

Answer 1

Water is polar, so amino acids exposed to aqueous environments will be polar. Similarly, the membrane is non-polar. Generally, amino acids on the inside of a "tight ball" with the exterior exposed to an aqueous environment will be polar. Think about what type of ion you would need to make a weak ionic bond with a negative ion...