Glutamate receptors are essential for synaptic transmission in the central nervous system. Regulating the trafficking of these receptors is one mechanism cells can use to control synaptic strength. Howard Chia-Hao Chang and Christopher Rongo have therefore analysed what directs assembly and transport of the nematode GLR1 and GLR2 proteins – glutamate receptor subunits closely related to the mammalian AMPA-type receptors (see ). The authors have introduced transgenes encoding mutated forms of GLR1 and GLR2 tagged with fluorescent proteins into wild-type and glr-mutant nematodes and monitored their transport by quantitative fluorescence microscopy. They find that GLR-1 and GLR-2 form a complex and that C-terminal tail sequences target these proteins to synapses. Significantly, wild-type GLRs can rescue targeting of mutant GLRs, presumably because intersubunit interactions allow them to escort their companions to synapses. The authors go on to show that the GLR-2 tail can direct a heterologous reporter protein to the synapse. Moreover, they demonstrate that this requires a PDZ-binding motif and other tail sequences, which interact with the synaptic protein LIN-10. Since many of these are evolutionarily conserved, the findings have important implications for receptor trafficking in vertebrates.
