Regulator of short-term neuronal synaptic plasticity in the dentate gyrus. Associates with AMPA receptors (ionotropic glutamate receptors) in synaptic spines and promotes AMPA receptor desensitization at excitatory synapses (By similarity). Component of some AMPA receptors (ionotropic glutamate receptors) complex, at least composed of some AMPA receptor (GRIA1, GRIA2 and/or GRIA3), CACNG2 and SHISA9, as well as low level of DLG4. Belongs to the shisa family. SHISA9 subfamily.