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Identification of mouse YB1/p50 as a component of the FMRP-associated mRNP particle
S Ceman1, R Nelson, S T Warren
1Department of Biochemistry, Howard Hughes Medical Institute, Atlanta, Georgia 30322, USA.
Abstract:
Fragile X mental retardation is caused by the absence of FMRP, an RNA-binding protein found in a large mRNP complex. Although there is evidence that FMRP exists as a homo-multimer, additional proteins have been identified that associate with FMRP in the mRNP. The autosomal paralogs of FMRP, FXR1P, and FXR2P, associate with FMRP, as do nucleolin and NUFIP1, all RNA binding proteins. Using cell lines that were stably transfected with Flag-Fmr1, we identified an additional protein that coimmunoprecipitates with FMRP. The approximately 50 kDa protein was identified by mass spectrometry as mouse Y box-binding protein 1 (YB1), which is 97% identical to the core mRNP protein p50, an RNA-binding protein. An anti-p50 antiserum recognized the 50 kDa protein, confirming the identification. The association of the FMRP-mRNP with a Y box protein, the latter commonly found in mRNPs, further suggests the involvement of FMRP in translation modulation.
Insights
Fragile X mental retardation is linked to FMRP absence. Researchers identified Y box-binding protein 1 (YB1) interacting with FMRP, suggesting a role in translation modulation.
Area of Science:
- Molecular Biology
- Neuroscience
- Genetics
Background:
- Fragile X mental retardation results from the absence of Fragile X mental retardation protein (FMRP).
- FMRP is an RNA-binding protein integral to messenger ribonucleoprotein (mRNP) complexes.
- While FMRP can form homo-multimers, other proteins like FXR1P, FXR2P, nucleolin, and NUFIP1 also associate with FMRP in mRNPs.
Purpose of the Study:
- To identify novel proteins interacting with FMRP within the mRNP complex.
- To further elucidate the molecular mechanisms underlying Fragile X mental retardation.
Main Methods:
- Stable transfection of cell lines with Flag-Fmr1.
- Co-immunoprecipitation assays to isolate FMRP-associated proteins.
- Mass spectrometry to identify co-immunoprecipitated proteins.
- Western blotting using anti-p50 antiserum for confirmation.
Main Results:
- A ~50 kDa protein was identified as mouse Y box-binding protein 1 (YB1) via mass spectrometry.
- YB1 is 97% identical to the core mRNP protein p50.
- Western blot analysis using anti-p50 antiserum confirmed the protein's identity as YB1/p50.
- This demonstrates a novel association between FMRP-mRNP and YB1.
Conclusions:
- The FMRP-mRNP complex associates with Y box-binding protein 1 (YB1).
- YB1 is a known component of mRNPs, strengthening its relevance in this context.
- This finding supports the hypothesis that FMRP plays a role in modulating translation.