The field of steroid hormone action has continued to expand into the realm of molecular biology at a pace even faster than most of us ever imagined. techniques of molecular biology have made it possible to clone The hormone-regulated genes and to examine steroid-receptor interactions with these genes. Nucleotide sequences of these genes, which show preferential binding of steroid receptors, have been identified. These results are complemented by the identification of chromatin acceptor proteins, which also show preferential binding for steroid-receptor complexes. Thus, one can envision the day when cloned genes, purified acceptor proteins, and receptor-steroid complexes will be recombined in vitro to form a functional unit. Cellular localization of steroid receptors has undergone recent revision, and it now appears that receptors are localized primarily in the nuclear compartment. These findings, although controversial, will lead to a reassessment of many of the previous concepts of steroid-receptor interactions and regulation. The way in which these observations at the of physiology, molecular and cellular levels fit into the overall scheme development, and evolution are continuing to progress, and the future promises some very exciting syntheses of understanding at all levels of biological organization. The third Meadow Brook Conference on hormones was held in order to bring together investigators who will undoubtedly contribute heavily to this future synthesis and to permit a free exchange of ideas and concepts as they relate to the current state-of-the-art in molecular endocrinology. Spring 1986 ARUN K. Roy JAMES H. CLARK Contents Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. v Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .