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. Belongs to the shisa family. SHISA9 subfamily. Extended N-terminus.