Fragile X syndrome is a common form of cognitive deficit caused by the functional absence
of fragile X mental retardation protein (FMRP), a dendritic RNA-binding protein that
represses translation of specific messages. Although FMRP is phosphorylated in a group I
metabotropic glutamate receptor (mGluR) activity-dependent manner following brief protein
phosphatase 2A (PP2A)-mediated dephosphorylation, the kinase regulating FMRP function
in neuronal protein synthesis is unclear. Here we identify ribosomal protein S6 kinase …