Axon/dendrite targeting of metabotropic glutamate receptors by their cytoplasmic carboxy-terminal domains

The subcellular targeting of neurotransmitter receptors is vital in control ling polarized information flow in the brain. We show here that metabotropi c glutamate receptors are differentially targeted when expressed from defec tive viral vectors in cultured hippocampal neurons; mGluR1a and mGluR2 are targeted to dendrites and excluded from axons, whereas mGluR7 is targeted t o axons and dendrites. Chimeras and deletions revealed that axon exclusion of mGluR2 versus axon targeting of mGluR7 is mediated by their 60 amino aci d C-terminal cytoplasmic domains. Addition of the mGluR7 C-terminal sequenc e to mGluR2! or to the unrelated somatodendritic protein telencephalin (tln ) induced axon targeting, indicating dominance of the axonal signal. These mGluR sorting signals represent novel plasma membrane axon/dendrite targeti ng signals.