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Two additional common subunits, ABC10 alpha and ABC10 beta, are shared by yeast RNA polymerases
1Service de Biochimie et de Génétique Moléculaire, Centre d'Etudes de Saclay, Gif-sur-Yvette, France.
The Journal of Biological Chemistry
|December 15, 1991
Summary
Yeast RNA polymerases share two small, distinct 10-kDa subunits, ABC10 alpha and ABC10 beta. These bona fide subunits, identified via chromatography and peptide analysis, are zinc-binding components of the enzymes.
Area of Science:
- Molecular Biology
- Biochemistry
- Yeast Genetics
Background:
- Yeast nuclear RNA polymerases are complex, multisubunit enzymes.
- Several small subunits are common to different RNA polymerase forms.
Purpose of the Study:
- To investigate the heterogeneity of the smallest subunit (10-kDa) common to yeast RNA polymerases A, B, and C.
- To identify and characterize the distinct polypeptides comprising this 10-kDa component.
Main Methods:
- Reverse-phase chromatography to resolve polypeptides.
- Electrophoresis, silver staining, and tryptic peptide analysis for characterization.
- Amino-terminal sequencing for identification.
Main Results:
- The 10-kDa component resolved into two distinct polypeptides: alpha and beta.
- Alpha polypeptides (A10, B10, C10) were indistinguishable across enzymes.
- Beta polypeptides (A10, B10, C10) were also indistinguishable and shared amino-terminal sequences with a known subunit.
- These two polypeptides, designated ABC10 alpha and ABC10 beta, were identified as bona fide subunits.
- Both ABC10 alpha and ABC10 beta were found to bind zinc.
Conclusions:
- Yeast RNA polymerases A, B, and C share two unique 10-kDa subunits, ABC10 alpha and ABC10 beta.
- These subunits are essential components of the respective RNA polymerase complexes.
- The zinc-binding property of these subunits may be significant for enzyme function.