Cited research: Science doi:10.1126/science.1191542 (2010)

Cystic fibrosis is caused by mutations in a protein called CFTR, which is found in cells' outer membranes. Attempts to express a functional version of the mutant protein have failed, partly because the rescued protein is rapidly degraded. Gergely Lukacs of McGill University in Montreal, Canada and his colleagues have identified the proteins that work together to eliminate this and other defective proteins from the outer membrane.

They found that a protein called Hsc70, helped by other molecular 'chaperones', recognize mutant CFTR at the cell surface that has not been properly folded into its three-dimensional structure. This biochemical pathway may serve as a back-up quality-control system for proteins that have escaped the cell's other 'housekeeping' methods, the authors say. H.L.