Expanding the Eukaryote's Cast of Chaperones

In order for proteins to function normally, they must fold into the correct three-dimensional shapes, a task they accomplish with the aid of special proteins called “chaperones.” Three papers in this issue ( pp.1713 , 1715 , and 1718 ) are now making it clear that, at least in higher organisms, protein folding is far more complex than researchers had suspected. It seems to involve a whole retinue of chaperone proteins, including certain members of the immunophilin family—among the first evidence of what the normal function might be for these proteins, which are best known as the targets of immunosuppressive drugs.