Figure 5.

Heuristic models of the interaction between mGluR5 and FMRP. Illustrated are simple logical relationships between FMRP and mGluR5-stimulated synaptic protein synthesis. A, a model in which FMRP or an FMRP-regulated protein specifically inhibits the signaling pathway that couples mGluR5 to translation. B, An alternative model in which signaling is unaffected in the absence of FMRP, but the consequences on protein synthesis are exaggerated. The results of the current investigation favor model B.