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

C-type particles ecreted in vivo by MOPC-315 myeloma ceils were characterized. These particles localize at a density of 1.16 g/ml in sucrose and possess a 6o to 7oS 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 7oS RNA as a template to synthesize DNA molecules which specifically hybridize to the homologous RNA