FMR1 PROTEIN - CONSERVED RNP FAMILY DOMAINS AND SELECTIVE RNA-BINDING

Fragile X syndrome is the result of transcriptional suppression of the gene FMR1 as a result of a trinucleotide repeat expansion mutation. T he normal function of the FMR1 protein (FMRP) and the mechanism by whi ch its absence leads to mental retardation are unknown. Ribonucleoprot ein particle (RNP) domains were identified within FMRP, and RNA was sh own to bind in stoichiometric ratios, which suggests that there are tw o RNA binding sites per FMRP molecule. FMRP was able to bind to its ow n message with high affinity (dissociation constant = 5.7 nM) and inte racted with approximately 4 percent of human fetal brain messages. The absence of the normal interaction of FMRP with a X syndrome.