Abstract
The F508 deletion in CFTR changes the proteins conformation, as a result of which it can no longer travel to the plasma membrane but is retained in the endoplasmic reticulum (ER). In search of new drugs to rescue the ?F508 phenotype many compound screens have been done and promising candidates have been identified, but their molecular mechanisms of action are still unknown. We developed an in vitro assay to follow conformational changes in CFTR and more specifically, in the F508-containing NBD1 domain. We subject in vitro translated radiolabeled NBD1 to limited proteolysis to examine conformational differences between wt and ?F508 NBD1. We clearly detect changes in conformation and are optimizing this assay further for examination of compound effects. To find out whether the screened compounds can affect NBD1 folding directly or indirectly we will add the drug at various stages of the limited proteolysis assay. Different compounds have been tested, including corrector 4a, which did not affect NBD1 folding. We concluded that these compounds do not rescue ?F508 CFTR by directly correcting NBD1, but must either affect CFTR domain assembly or act by changing the cell, for instance by activating a crucial chaperone