Prions common in yeast.

Prions may be more widespread than previously thought, researchers at the Whitehead Institute for Biomedical Research in Cambridge, Mass., report in the April 3 Cell. Baker's yeast was previously known to have six native prion proteins, none of which appear harmful. A team led by Howard Hughes Medical Institute investigator Susan Lindquist found that 19 other proteins contain prion-forming domains--a structure that allows the protein to change its shape and function, and to spread the altered form to other proteins. One of the proteins, Mot3p, was fully characterized and found to meet all criteria for a prion. "It is logical to suggest that there are even more prions around," says Yury Chernoff of the Georgia Institute of Technology in Atlanta.