National Institutes of Health Lectures in Biomedical Sciences: Current Topics in Biochemistry is based on a series of lectures dealing with current topics in biochemistry and more biologically or medically oriented topics. These lectures were organized for the benefit of young physicians who had just finished their clinical training but were several years out-of-date with respect to basic scientific research. The lecturers were asked, therefore, to present not only their own contributions to the field but also a broad review of recent developments in a large area of science. The lectures were surprisingly well attended not only by the associates for whom they had originally been designed but also by a large fraction of the NIH research community, specialists and nonspecialists alike. The lectures in this volume cover the following topics: genetic control of lipid metabolism; mammalian RNA-containing tumor viruses; current directions in research on cyclic AMP; the chemistry and biology of collagen; properties of the protein complex of striated muscle involved in the contractile process; cell surface receptor sites; and membrane structure and function.