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RNA-instructed DNA polymerase associated with C-type particles produced in vivo by murine myeloma cells
Abstract:
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.
Insights
Researchers characterized C-type particles from myeloma cells, finding they contain RNA and an RNA-instructed DNA polymerase. This enzyme synthesizes DNA using the viral RNA template, crucial for understanding retroviral replication.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- MOPC-315 myeloma cells secrete C-type particles in vivo.
- Characterization of these particles is essential for understanding their biological role.
Purpose of the Study:
- To characterize the biochemical properties of C-type particles secreted by MOPC-315 myeloma cells.
- To investigate the enzymatic activity and template usage of the associated DNA polymerase.
Main Methods:
- Density gradient centrifugation in sucrose to determine particle localization.
- Analysis of RNA content and identification of RNA-instructed DNA polymerase activity.
- Enzyme assays to determine cofactor requirements and inhibitors.
Main Results:
- C-type particles localized at a density of 1.16 g/ml in sucrose.
- Particles contained 60-70S RNA and an RNA-instructed DNA polymerase.
- Enzyme activity required manganese, was inhibited by ribonuclease, and depended on deoxynucleoside triphosphates.
Conclusions:
- The identified enzyme utilizes the viral 60-70S RNA as a template.
- Synthesized DNA molecules specifically hybridize to the homologous RNA, indicating reverse transcription.
- These findings contribute to the understanding of retroviral replication mechanisms in myeloma cells.