In addition to pore-forming subunits, native AMPARs incorporate multiple auxiliary subunits that regulate AMPAR membrane trafficking, synaptic targeting, gating and signaling (Haering et al., 2014). TARP, SHISA and CNIH family auxiliary subunits show striking cell specific expression patterns (Figure 4C–E). TARPγ2 is enriched in PV cells, TARPγ3, γ8 and SHISA6 are enriched in SST/CR cells, TARPγ3 and SHISA9 are enriched in VIP/CCK cells. While PV cells predominantly express one auxiliary subunit (TARPγ2), SST/CR cells express at least 6 types (TARPγ2, γ3, γ8, γ5, γ7, SHISA6). Whereas pore-subunits differ in expression levels, auxiliary subunits often show ON/OFF expression among PCPs (Figure 4E). Thus different GABAergic neurons may assemble a specific set of native AMPARs with distinct pore and auxiliary subunit compositions, postsynaptic distribution patterns and biophysical properties. This large repertoire of native AMPARs may achieve cell type- and synapse- specific transmission and plasticity of glutamatergic inputs according to different presynaptic sources.
