Some proteins lead double or even quadruple lives. In 1994, researchers discovered the gene responsible for Wiskott Aldrich syndrome, an X-linked genetic disorder in which affected patients generally succumb to infections or cancer. Because of the observed immune dysfunction, the protein, called WASP, was believed to regulate lymphocytes or platelets.1
But, challenging the traditionally held one-protein-one-function notion, subsequent studies found that WASP had several jobs, among them organizing cellular actin skeletons and communicating between the immune system's T and B cells.2 This multifunctionality, considered an oddity a decade ago,3 might explain the disorder's wide array of manifestations. It turns out, however, that WASP's multitasking is not an anomaly at all. Multifunctional or "moonlighting" proteins have turned out to be surprisingly common, and examples of proteins with as many as five proposed functions have emerged.4
"People had had a notion for many, many years that some proteins had more than one ...
