In Cystic Fibrosis Patients, Deletion of an Amino Acid (Phenylalanine

In cystic fibrosis patients, deletion of an amino acid (phenylalanine 508) in the CFTR protein

A) disrupts the normal interactions of CFTR with chaperones in the endoplasmic reticulum, leading to defective protein folding and reduced levels of functional CFTR in the plasma membranes of affected cells.
B) leads to misfolded proteins, which aggregate to form insoluble amyloid fibrils characterized by β-sheet structures.
C) precludes CFTR phosphorylation by a protein kinase, which is necessary for activation of this protein.
D) prevents ATP hydrolysis required for the active transport of Cl^- by CFTR.