Genetic regulation of development involves the coordinated activities of two multi-protein complexes. One complex assembles at the promoter sequence, proximal to the start site of transcription. This complex, termed the general transcription complex, is comprised of RNA polymerase and the associated TF factors which modulate the polymerase's activity. The second complex, situated 10 to 50,000 basepairs away, is known as the enhancer complex or enhanceosome. The DNA sequence of the enhancer contains binding sites for a small set of proteins, typically no more than 10 distinct types, which define the specificity of the activation event at the promoter. However, what it means to activate expression of a specific gene remains unknown. Current state of knowledge suggests the role of the enhancer is to promote recruitment of polymerase to the promoter. This suggests that the study of the physical interactions may provide a fundamental insight into the mechanism of activation. Our laboratory is exploring structure/function relationships between proteins which make up each of these complexes, as well as the proteins (termed co-activators) which can bridge the 'communication gap' between promoters and enhancers.