FMR1 Protein Summary

Fragile X messenger ribonucleoprotein 1 (FMR1) is a multifunctional RNA-binding protein of 632 amino acids that regulates neuronal development and synaptic plasticity (UniProt: Q06787). It controls alternative mRNA splicing, mRNA stability, dendritic transport, and postsynaptic protein synthesis through formation of phase-separated ribonucleoprotein granules. FMR1 binds specific mRNA sequences (ACU[GU] and [AU]GGA motifs) and G-quadruplex structures, modulating both translation repression and activation of target dendritic mRNAs in response to metabotropic glutamate receptor signaling.

FMR1 functions broadly in the nervous system, stabilizing key synaptic proteins including PSD-95 and regulating ion channel activity and microtubule dynamics. It also participates in mRNA nuclear export, DNA damage response signaling, and miRNA-mediated translational control. Beyond neurology, FMR1 mutations cause fragile X syndrome and fragile X tremor/ataxia syndrome, and are associated with premature ovarian failure.

FMR1 is classified by SFARI as a Category S (syndromic) gene with strong evidence for autism association (SFARI Cat S). Loss of FMR1 function in fragile X syndrome represents one of the most common monogenic causes of autism spectrum disorder and intellectual disability, making this protein central to understanding syndromic autism pathogenesis.