The cellular phenotype of the most common cystic fibrosis-causing mutation, deletion of
phenylalanine 508 (ΔF508) in the amino-terminal nucleotide binding domain (NBD1) of the
cystic fibrosis transmembrane conductance regulator (CFTR), is the inability of the mutant
protein to fold and transit to the apical membrane of affected epithelial cells. Expressed
NBD1s were purified and folded in vitro into soluble monomers capable of binding
nucleotide. Here we report that the ΔF508 mutation has little effect on the thermodynamic …