Journal Article

The Fragile X Mental Retardation Protein is Associated with Poly(A)<sup>+</sup> mRNA in Actively Translating Polyribosomes

François Corbin, Marlène Bouillon, Anny Fortin, Stanislas Morin, François Rousseau and Edouard W. Khandjian

in Human Molecular Genetics

Volume 6, issue 9, pages 1465-1472
Published in print September 1997 | ISSN: 0964-6906
Published online September 1997 | e-ISSN: 1460-2083 | DOI:
The Fragile X Mental Retardation Protein is Associated with Poly(A)+ mRNA in Actively Translating Polyribosomes

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The fragile X syndrome results from a transcriptional silencing of the FMR1 gene and the absence of its encoded protein. FMRP is a cytoplasmic RNA-binding protein, whose specific cellular function is still unknown. We present evidence that virtually all detectable cytoplasmic FMRP in mouse NIH 3T3 and human HeLa cells is found strictly in association with mRNA in actively translating polyribosomes. Furthermore, FMRP released from polyribosomes is associated with ribonucleoprotein complexes with sedimentation coefficients of 60–70S and selection on oligo(dT)-cellulose reveals that this association is specific to poly(A)-containing mRNPs. This association with actively translating polyribosomes is not affected by alteration of translational processes induced by serum stimulation and starvation in NIH 3T3 cells, suggesting that FMR1 expression is not cell cycle regulated and that FMRP might have a house-keeping function. FXR2 protein, which is closely related to FMRP, is also detected associated with mRNPs in translating polyribosomes. The results strongly suggest that FMRP might be a mRNA chaperone interacting with mRNP complexes.

Journal Article.  6507 words.  Illustrated.

Subjects: Genetics and Genomics

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