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Effect of the multicatalytic proteinase (prosome) on translational activity in rabbit reticulocyte lysates
1Diabetes Forschungsinstitut, Düsseldorf, FRG.
Abstract:
In a message-dependent reticulocyte lysate translation system, incorporation of [3H]leucine into acid-insoluble protein is increased following selective removal of the multicatalytic proteinase (MCP) with a monospecific antibody. Re-addition of active proteinase to previously depleted lysates reverses this effect in that the same low levels of translational product are measured as in untreated lysates. Addition of histone-stimulated MCP further depresses the level of protein product. Conversely, lysates supplemented with inactivated MCP retain the higher level of translational activity which is measured after precipitation of the enzyme with antibody. In these lysates, the effect of the antibody on translational activity is inversely correlated with that on hydrolytic activity towards [14C]methylcasein or N-succinyl-Leu-Leu-Val-Tyr-4-methyl-7-coumarylamide, two substrates of the MCP. These results showing that the MCP is capable of modulating translational activity in vitro, suggest an important role of this molecule in the in vivo translational process.
Insights
The multicatalytic proteinase (MCP) regulates protein synthesis. Removing MCP enhances translation, while adding active MCP decreases it, suggesting MCP
Area of Science:
- Molecular Biology
- Protein Synthesis Regulation
- Enzymology
Background:
- Protein synthesis is a fundamental cellular process.
- The role of proteases in regulating translation is not fully understood.
- The multicatalytic proteinase (MCP) is a key enzyme complex.
Purpose of the Study:
- To investigate the effect of multicatalytic proteinase (MCP) on in vitro protein translation.
- To determine if MCP modulates the activity of the translation machinery.
Main Methods:
- Utilized a message-dependent reticulocyte lysate translation system.
- Selective removal of MCP using a monospecific antibody.
- Assessed protein synthesis by measuring [3H]leucine incorporation.
- Measured MCP hydrolytic activity using specific substrates.
Main Results:
- Removal of MCP significantly increased [3H]leucine incorporation into proteins.
- Re-addition of active MCP reversed this effect, lowering protein synthesis.
- Inactivated MCP did not affect the enhanced translational activity observed after antibody precipitation.
Conclusions:
- The multicatalytic proteinase (MCP) directly modulates protein translation in vitro.
- These findings suggest a significant regulatory role for MCP in vivo protein synthesis.