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. Author manuscript; available in PMC: 2015 Feb 13.
Published in final edited form as: Annu Rev Neurosci. 2012 Apr 5;35:417–443. doi: 10.1146/annurev-neuro-060909-153138

Figure 4.

Figure 4

FMRP regulates mRNA translation. FMRP (red ovals) can be found bound to coding regions of mRNA in association with stalled ribosomes [complexes of 40S (small gray ovals) and 60S (large gray ovals) ribosomal subunits] and bound to 3′UTRs in association with inhibitory components of the initiation machinery (indicated by an inhibitory line). Data currently suggest that FMRP normally represses translation by stalling the elongation of actively translating ribosomes and by blocking the initiation of ribosome assembly. Loss of FMRP (as in fragile X) removes both of these inhibitory associations and leads to increased protein synthesis. Curly blue lines represent ribosomally synthesized polypeptide chains that lengthen as translation proceeds. Small arrows indicate active movement. Abbreviations: AUG, initiation codon; FMRP, fragile X mental retardation protein; m7G, 7-methylguanylate cap; ON, translation on; OFF, translation off; UAG, termination codon; 3′UTR, 3 prime-end untranslated region.