Nature Structural Biology pages 602-608 There are times when cell death is a good thing. During viral infection, for example, cell death can thwart an invading virus by depriving it of a hospitable place to thrive. Likewise, unwanted cells are destroyed during development, metamorphosis, and tissue turnover. This orderly process is known as programmed cell death or apoptosis. Cell death figures prominently in the functioning of the immune and nervous systems.
Apoptosis is also an important mechanism for eliminating cancerous cells.
While a variety of signals can trigger apoptosis, there are also a number of inhibitors of apoptosis. One example of such an inhibitor is a human protein known as survivin that is expressed at the start of cell division. High levels of survivin are found in the developing embryo and in many common human cancers, including lung, colon, pancreas, prostate, and breast cancer. This finding makes it a novel target for cancer therapy. To try to understand how this protein inhibits apoptosis and promotes tumor cell survival, Joseph Noel, of the Structural Biology Laboratory at The Salk Institute for Biological Studies in La Jolla, California, USA, and his coworkers have now solved its structure by X-ray crystallography.