We plan to continue our studies on the characterization of proteins involved in DNA replication in vitro. For this purpose we shall utilize the conversion of phi X single-stranded DNA to RFII structures. Utilizing this system, we have purified 9 proteins which are involved in this reaction. These purified proteins, in the presence of ATP, the 4 dXTPs and phi X single-stranded DNA catalyze RFII formation. We are now attempting to disect this system more systematically in order to define the biochemical reactions catalyzed by each of these proteins. We plan to examine the role of ATP (or dATP) in the elongation reaction of DNA or RNA primers hydrogen-bonded to long chain DNA primers. This reaction requires DNA polymerase III (or II) and Factor I and Factor II. We plan to further characterize the mechanism involved in this elongation reaction. Studies on the synthesis of oncornaviral RNA will continue. We will determine whether nucleoplasmic RNA polymerase (alpha-amanitin sensitive) synthesize long chain RNA products from myeloblast chromatin which contain the 35S RNA sequence of avian myeloblastosis virus. We shall continue experiments designed to synthesize heterogeneous RNA in vitro.