We plan to investigate some interactions and mechanisms of cell biology that are important to an understanding of oncogenic transformation, especially as it relates to the cell envelope. The three organelles in which we have particular interest are chromatin, microfilaments, and the plasma membrane. To approach an understanding of these eukaryotic systems we shall initially use the filamentous viruses. Much more readily than the target organelles themselves, this unique system can be studied by x-ray diffraction of partially ordered systems, and by model building at the level of molecular structure. The filamentous virus proteins are also involved in DNA replication, which we shall study using subcellular systems. With detailed structural information about filamentous viruses, we shall be in a position to study the structure and function of eukaryotic organelles, and their role in oncogenic transformation.