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Particulate protein-synthesis factors associated with translatable mRNA in mouse hybridoma cells
Abstract:
Besides of mRNA, the postribosomal pellet of mouse hybridoma cells contains RNA species which become labeled more rapidly than rRNA. Their synthesis is inhibited by actinomycin D. Density-gradient centrifugation of the postribosomal pellet yielded fractions of approx. 55-60 and 90S, synthesizing after the addition of both ribosomal subunits and energy-sources light and heavy chains of immunoglobulin, as demonstrated by indirect immunoprecipitation. Analysis of translation products by electrophoresis indicated the presence of precursors of mRNAs for immunoglobulin chains in these particles. Postribosomal pellets thus apparently contain different particles composed of similar polypeptide chains and containing protein-synthesis factors associated with translatable mRNA.
Insights
Mouse hybridoma cells contain unique RNA species in their postribosomal pellet, including messenger RNA precursors for immunoglobulin chains. These particles associate with protein synthesis factors, aiding in immunoglobulin production.
Area of Science:
- Molecular Biology
- Cell Biology
- Immunology
Background:
- Ribosomal pellets in mouse hybridoma cells contain RNA species beyond mature mRNA.
- These RNA species exhibit rapid labeling and are sensitive to actinomycin D, suggesting active synthesis.
- Understanding these components is crucial for elucidating protein synthesis regulation.
Purpose of the Study:
- To identify and characterize novel RNA species within the postribosomal pellet of mouse hybridoma cells.
- To investigate the role of these RNA species in the synthesis of immunoglobulin chains.
- To determine the composition and function of particles associated with translatable mRNA.
Main Methods:
- Density-gradient centrifugation to isolate RNA fractions.
- Indirect immunoprecipitation to identify synthesized immunoglobulin chains.
- Electrophoresis to analyze translation products and mRNA precursors.
Main Results:
- Postribosomal pellets contained distinct fractions (approx. 55-60S and 90S) actively synthesizing immunoglobulin light and heavy chains.
- Analysis revealed the presence of messenger RNA precursors for immunoglobulin chains within these fractions.
- These particles were found to associate with protein synthesis factors and translatable mRNA.
Conclusions:
- Mouse hybridoma postribosomal pellets harbor distinct particles containing mRNA precursors for immunoglobulin synthesis.
- These particles are functionally associated with protein synthesis machinery.
- The findings shed light on the regulation of immunoglobulin production at the post-transcriptional level.