The FMR-1 protein is cytoplasmic, most abundant in neurons and appears normal in carriers of a fragile X premutation

Nat Genet. 1993 Aug;4(4):335-40. doi: 10.1038/ng0893-335.


Fragile X mental retardation syndrome is caused by the unstable expansion of a CGG repeat in the FMR-1 gene. In patients with a full mutation, abnormal methylation results in suppression of FMR-1 transcription. FMR-1 is expressed in many tissues but its function is unknown. We have raised monoclonal antibodies specific for the FMR-1 protein. They detect 4-5 protein bands which appear identical in cells of normal males and of males carrying a premutation, but are absent in affected males with a full mutation. Immunohistochemistry shows a cytoplasmic localization of FMR-1. The highest levels were observed in neurons, while glial cells contain very low levels. In epithelial tissues, levels of FMR-1 were higher in dividing layers. In adult testis, FMR-1 was detected only in spermatogonia. FMR-1 was not detected in dermis and cardiac muscle except under pathological conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal
  • Base Sequence
  • Cell Line
  • Cloning, Molecular
  • DNA / genetics
  • DNA / metabolism
  • Exons
  • Fragile X Mental Retardation Protein
  • Fragile X Syndrome / genetics*
  • Fragile X Syndrome / metabolism
  • Genetic Carrier Screening*
  • Humans
  • Male
  • Methylation
  • Molecular Sequence Data
  • Mutation*
  • Nerve Tissue Proteins / biosynthesis
  • Nerve Tissue Proteins / genetics*
  • Nerve Tissue Proteins / metabolism*
  • Neurons / metabolism*
  • Oligodeoxyribonucleotides
  • Organ Specificity
  • RNA-Binding Proteins*
  • Recombinant Fusion Proteins / analysis
  • Recombinant Fusion Proteins / biosynthesis
  • Repetitive Sequences, Nucleic Acid
  • Transfection


  • Antibodies, Monoclonal
  • FMR1 protein, human
  • Nerve Tissue Proteins
  • Oligodeoxyribonucleotides
  • RNA-Binding Proteins
  • Recombinant Fusion Proteins
  • Fragile X Mental Retardation Protein
  • DNA