The CFTR protein is made up of 1,480 amino acids linked together in a chain. Some

humans produce a version of the CFTR protein in which phenylalanine (an amino acid)

has been deleted from position 508 of the amino acid chain.

Which of the following best predicts how the amino acid deletion will affect the structure of

the CFTR protein?

It will have no observable effect on the structure of the CFTR protein.

It will affect the primary structure of the CFTR protein, but the other levels of protein

structure will not be affected.

It will affect the secondary and tertiary structures of the CFTR protein, but the primary

structure will not be affected.

D) It will affect the primary, secondary, and tertiary structures of the CFTR protein.

The answer is D) It will affect the primary, secondary, and tertiary structures of the CFTR protein.

Explanation:

The deletion of phenylalanine (F) in position 508 or F508, disrupts the sequence of amino acids and polypeptides, as seen in the primary structure.

It also affects the secondary structure since it can alter the folding or kinks of the alpha-helices or beta-sheets of the local polypeptide chain.

For the tertiary structures, it will affect the overall shape of the CFTR protein, and ultimately, alter its function in the body which is to produce thin, free-flowing mucus in the respiratory, digestive, and reproductive system, etc.

What is the CFTR Protein?

Normally, the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein functions as a membrane channel protein that transports negatively-charged ions, such as chloride ions, in and out of the cell. It also transports water which is used to form thin, free-flowing mucus seen in the respiratory, digestive, and reproductive systems. It can also influence other channels to regulate the entry of sodium ions across plasma membranes seen in the pancreas and lungs.

The CFTR protein mutation found in Cystic Fibrosis (CF) is present in almost 70% of CF patients. The mutation alters the structure of the chloride ion channel and movement of chloride ions and water in and out of the cell. Thus, impairing the production of mucus, which is characteristically sticky and thick seen in Cystic Fibrosis.