RNA instructed DNA polymerase associated with C type particles produced in vivo by murine myeloma cells

C type particles secreted in vivo by MOPC 315 myeloma cells were characterized. These particles localize at a density of 1.16 g/ml in sucrose and possess a 60 to 70S RNA and an RNA instructed DNA polymerase. Endogenous enzyme activity requires manganese and is inhibited by ribonuclease or by the omission of any of the deoxynucleoside triphosphates. The enzyme utilizes the virus 60 to 70S RNA as a template to synthesize DNA molecules which specifically hybridize to the homologous RNA.