Togetherness, molecular style

One way to switch the function of a cell surface protein is to force it into a different membrane domain. On page 647, Nicholson and Stanners describe a second method: diluting it within its domain with an abundance of defective partners. The approach might provide a way to neutralize a protein that is overproduced in most cancers.

Some surface proteins lie completely outside the cell, attached by molecules called glycophosphatidyl inositols (GPIs). These anchors dictate protein function by steering their proteins into particular membrane domains called rafts, clusters crucial for transmitting signals. Nicholson and Stanners tested whether dilution of raft clustering could thwart CEA, an adhesion protein whose overexpression in many cancers blocks differentiation and allows tumor cells to continue dividing.

The researchers worked with two hybrid proteins. One,...