Although malformed prions are known to cause "mad cow" disease and other incurable brain diseases known as transmissible spongiform encephalopathies (TSEs), the role of normal prions has remained enigmatic. But new research reported in today's issue of the journal Science reveals a possibility: in its nonpathogenic form, the scrapie prion may help to fine-tune nerve cell function through cellular signaling.

Seated comfortably on a nerve cell's surface, normal prions, along with a few other proteins, seem to take part in a chain of signaling events that activates the so-called Fyn enzyme, which can then initiate events inside the cell. Further dissecting this signal-carrying pathway, the researchers say, will help identify what stimulates prion activity. That, in turn, should illuminate how the maverick form destroys cellular processes--information that might one day lead to treatment