Novel pharmacological strategies to treat cystic fibrosis John W. Hanrahan, Heidi M. Sampson, David Y. Thomas  Trends in Pharmacological Sciences  Volume 34, Issue 2, Pages 119-125 (February 2013) DOI: 10.1016/j.tips.2012.11.006 Copyright © 2012 Elsevier Ltd Terms and Conditions

Figure 1 Overall organization of the cystic fibrosis transmembrane conductance regulator (CFTR). A cartoon depicting our current understanding of the structure of CFTR within the membrane is shown. The most common mutation in CFTR (ΔF508) is located within the first nucleotide-binding domain (NBD1) and makes important contacts with intracellular loops from the second membrane-spanning domain (MSD2). Trends in Pharmacological Sciences 2013 34, 119-125DOI: (10.1016/j.tips.2012.11.006) Copyright © 2012 Elsevier Ltd Terms and Conditions

Figure 2 Trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR) and mutant ΔF508-CFTR in cells. The overall biosynthetic pathway for CFTR and important checkpoints are indicated. Nascent CFTR is translocated into the endoplasmic reticulum (ER), where it undergoes core N-glycosylation and folding in the calnexin cycle. Correctly folded protein proceeds along the biosynthetic pathway for export to the Golgi apparatus, where complex glycosylation occurs, and then subsequently to the plasma membrane, where it functions as a chloride and bicarbonate channel. Terminally misfolded folded protein is shunted from the calnexin cycle to become degraded in the proteasome via ER-assisted protein degradation (ERAD). It may also trigger the unfolded protein response. Another quality control checkpoint exists at the periphery of the cell to monitor CFTR at recycling and internalization steps, which targets incorrectly folded protein for degradation through the lysosome. Trends in Pharmacological Sciences 2013 34, 119-125DOI: (10.1016/j.tips.2012.11.006) Copyright © 2012 Elsevier Ltd Terms and Conditions

Figure 3 Maturation of the cystic fibrosis transmembrane conductance regulator (CFTR). A western blot of CFTR and ΔF508-CFTR protein expressed in baby hamster kidney (BHK) cells is shown. The core-glycosylated immature form (band B) and complex glycosylated mature form (band C) of CFTR are indicated with arrows. Trends in Pharmacological Sciences 2013 34, 119-125DOI: (10.1016/j.tips.2012.11.006) Copyright © 2012 Elsevier Ltd Terms and Conditions