The battle of the fold: chaperones take on prions.

Protein conformational diseases, such as Alzheimer's, Parkinson's and Huntington's, affect a large portion of our aging population. Cells have evolved mechanisms for rescuing and recycling misfolded proteins, but these systems are not perfect. Chaperones can rescue misfolded proteins by breaking up aggregates and assisting in the refolding process. Proteins that cannot be rescued by refolding can be delivered to the proteasome by chaperones to be recycled. One class of 'misfolded' proteins, prions, appears to evade detection by this machinery and persist in a misfolded state. In fact, it seems that the prions usurp the refolding machinery and actually employ chaperones to propagate the prion state. Recent data has begun to uncover the mechanism behind this unique relationship.