Abstract
Many problems in modern biology involve complex arrays of interacting protein and, in some cases, RNA molecules. The initial challenge facing investigators is to identify the important players that drive the process under study. This difficult task is ameliorated somewhat by the development of methods designed to keep pace with the magnitude of this challenge. I have outlined a few of these approaches at the cutting edge of cloning interacting proteins. A perhaps more daunting prospect is to dissect the important molecules once they are in hand, to identify key interactions, and, ultimately, to move to an understanding of function in cells. For this, of course, all of the tools of genetics, biochemistry, and molecular biology, extant and yet to be developed, will have to be tapped.