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The mouse poly(C)-binding protein exists in multiple isoforms and interacts with several RNA-binding proteins
B Funke1, B Zuleger, R Benavente
1Institut für Virologie und Immunbiologie der Universität Würzburg, Germany.
Abstract:
The murine poly(C)-binding protein (mCBP) was previously shown to belong to the group of K-homology (KH) proteins by virtue of its homology to hnRNP-K. We have isolated cDNA-splice variants of mCBP which differ by two variable regions of 93 bp and/or 39 +/- 3 bp respectively. Both variable regions are located between the second and third KH-domain of mCBP. The characterization of a partial genomic clone enabled us to propose a model for the generation of the second variable region by the use of a putative alternative splice signal. The mCBP mRNA is expressed ubiquitously and the protein is found predominantly in the nucleus with the exception of the nucleoli. We have identified five proteins which interact with mCBP in the yeast two hybrid system: mouse y-box protein 1 (msy-1), y-box-binding protein, hnRNP-L, filamin and splicing factor 9G8. The interaction between mCBP and splicing factor 9G8 was confirmed in vivo. These results suggest a function of mCBP in RNA metabolism.
Insights
Murine poly(C)-binding protein (mCBP) splice variants were identified, differing in two variable regions. These variants, interacting with several proteins, suggest a role for mCBP in RNA metabolism.
Area of Science:
- Molecular Biology
- RNA Biology
- Protein Interactions
Background:
- Murine poly(C)-binding protein (mCBP) is homologous to hnRNP-K, classifying it as a K-homology (KH) protein.
- Previous studies established mCBP's homology to hnRNP-K, placing it within the KH protein family.
Purpose of the Study:
- To isolate and characterize cDNA splice variants of mCBP.
- To investigate the genomic basis for alternative splicing in mCBP.
- To identify proteins interacting with mCBP and elucidate its cellular function.
Main Methods:
- cDNA isolation and characterization of splice variants.
- Genomic clone analysis to model alternative splicing.
- Yeast two-hybrid system for protein-protein interaction studies.
- In vivo validation of protein interactions.
Main Results:
- Isolated mCBP cDNA splice variants differing by two variable regions (93 bp and 39 bp).
- Proposed a model for alternative splicing generating the second variable region.
- Identified five interacting proteins: msy-1, y-box-binding protein, hnRNP-L, filamin, and splicing factor 9G8.
- Confirmed in vivo interaction between mCBP and splicing factor 9G8.
- Ubiquitous mCBP mRNA expression with nuclear localization (excluding nucleoli).
Conclusions:
- mCBP exhibits alternative splicing, generating distinct protein variants.
- mCBP interacts with multiple proteins involved in RNA processing.
- These findings strongly suggest a functional role for mCBP in RNA metabolism.