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Sequence comparison among subunits of multicatalytic proteinase
H Sorimachi1, H Kawasaki, T Tsukahara
1Department of Molecular Biology, Tokyo Metropolitan Institute of Medical Science, Japan.
Biomedica Biochimica Acta
|January 1, 1991
Summary
Multicatalytic proteinase (MCP) subunits
Area of Science:
- Molecular biology
- Biochemistry
- Proteomics
Background:
- The primary structures of multicatalytic proteinase (MCP) subunits have been elucidated through cDNA cloning and characterization.
- The catalytic mechanism underlying MCP's multicatalytic activity, particularly its protease functions, remains poorly understood.
- No homology to known protease sequences has been identified within the determined MCP subunit sequences.
Purpose of the Study:
- To propose a structural model explaining the obscure catalytic mechanism of multicatalytic proteinases (MCPs).
- To reconcile the lack of identifiable protease sequences in MCP subunits with their known enzymatic activities.
Main Methods:
- cDNA cloning and characterization of multicatalytic proteinase (MCP) subunits.
- Primary structure determination of MCP subunits.
- Development of a hypothetical structural model for MCP function.
Main Results:
- The primary structures of several multicatalytic proteinase (MCP) subunits have been determined.
- A novel structural model for MCP is proposed, comprising two subunit classes: structural and catalytic.
- The proposed model suggests structural subunits form a container for catalytic subunits, facilitating substrate reactions.
Conclusions:
- The proposed structural model offers a potential explanation for the multicatalytic nature of MCPs, despite the absence of recognizable protease motifs.
- This model effectively accounts for existing experimental observations regarding MCP function.
- Further investigation is warranted to validate this hypothesis and explore alternative explanations.