The GRM5 gene at 11q14.2-q14.3 codes for the 1212 amino acid propeptide of the metabotropic glutamate receptor 5 which modulates excitatory neurotransmission. There are two isoforms from alternate splicing. It interacts with fragile X mental retardation protein 1. This may be relevant to some of the symptoms of autism. Receptor stimulation prevents neuronal apoptosis.