A molecular Dr. Jekyll finally has a day job—as an electrical lineman. A new study suggests that the normal form of prion protein helps maintain the insulation that speeds electrical signals along nerve fibers.

In its twisted Mr. Hyde form, the prion protein causes fatal brain-wasting diseases, such as mad cow disease in cattle and Creutzfeldt-Jakob disease in people. But the normal form of the protein, which is typically found in neurons in people and other mammals, is also a good guy, a new study shows. The protein may direct cells called Schwann cells to wrap around neurons and produce myelin, a type of insulation that aids electrical communication between nerve cells. This newly discovered role for the normal form of the prion protein — designated PrP(C) or just PrP — could link the protein to nerve disorders called peripheral neuropathy, researchers led by Adriano Aguzzi, a neuropathologist at the University of Zurich, report in the Jan. 24 Nature Neuroscience.