A fundamental feature of life is the interaction between its component parts, without which life would not exist. Interaction occurs at all levels. At the molecular level, proteins and nucleic acids form complexes that create the structural and functional entity, which is the cell. Cells interact to form multicellular organisms (eukaryotes) or communities (prokaryotes). At both the molecular and cellular levels, interaction involves communication in addition to association. It is by way of these communications that most of the miracles of nature are achieved. We are interested in understanding how molecules and cells coordinate their activities to achieve functions that they cannot do individually.