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Updated: Jul 22, 2026

A Robust Polymerase Chain Reaction-based Assay for Quantifying Cytosine-guanine-guanine Trinucleotide Repeats in Fragile X Mental Retardation-1 Gene
08:22

A Robust Polymerase Chain Reaction-based Assay for Quantifying Cytosine-guanine-guanine Trinucleotide Repeats in Fragile X Mental Retardation-1 Gene

Published on: September 16, 2019

Different targets for the fragile X-related proteins revealed by their distinct nuclear localizations

F Tamanini1, C Bontekoe, C E Bakker

  • 1Department of Clinical Genetics and Center for Biomedical Genetics, Erasmus University, PO Box 1738, 3000 DR Rotterdam, The Netherlands.

Human Molecular Genetics
|April 10, 1999
PubMed

Insights

Fragile X mental retardation protein (FMRP) and its homologs shuttle between the nucleus and cytoplasm. Polyribosome association regulates this movement, impacting RNA transport in Fragile X syndrome.

Area of Science:

  • Molecular biology
  • Cell biology
  • Genetics

Background:

  • Fragile X syndrome results from the absence of fragile X mental retardation protein (FMRP).
  • FMRP, FXR1P, and FXR2P form a family of RNA-binding proteins (FXR proteins) that associate with polyribosomes as cytoplasmic mRNP particles.
  • Understanding FXR protein localization and transport is crucial for comprehending Fragile X syndrome pathogenesis.

Purpose of the Study:

  • To investigate the nucleocytoplasmic shuttling of FXR proteins.
  • To determine the role of polyribosome association in regulating FXR protein transport.
  • To identify the nuclear export mechanisms and specific shuttling routes of FXR proteins.

Main Methods:

  • Utilized cell culture and biochemical assays to study FMRP, FXR1P, and FXR2P.
  • Employed leptomycin B to inhibit CRM1-mediated nuclear export.
  • Inactivated nuclear export signals to dissect specific shuttling pathways.

Main Results:

  • FMRP, FXR1P, and FXR2P were found to shuttle between the cytoplasm and nucleus.
  • A disease-associated FMRP mutant (FMRPI304N) showed reduced polyribosome association and increased nuclear shuttling.
  • Exportin 1 mediates the nuclear export of FXR proteins, with FMRP shuttling between cytoplasm and nucleoplasm, and FXR2P between cytoplasm and nucleolus.

Conclusions:

  • Polyribosome association regulates the nucleocytoplasmic shuttling of FXR proteins.
  • FXR proteins utilize distinct shuttling routes, suggesting specialized roles in RNA transport.
  • These findings provide insights into the molecular mechanisms underlying Fragile X syndrome.

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