Enables PDZ domain binding activity. Involved in regulation of AMPA receptor activity; regulation of postsynaptic neurotransmitter receptor activity; and regulation of short-term neuronal synaptic plasticity. Located in glutamatergic synapse; postsynaptic density; and synaptic membrane. Part of AMPA glutamate receptor complex. Is integral component of postsynaptic density membrane. Is expressed in brain. Orthologous to human SHISA9 (shisa family member 9). [provided by Alliance of Genome Resources, Apr 2022]