Enables channel regulator activity. Involved in regulation of AMPA receptor activity. Acts upstream of or within glutamatergic synaptic transmission and regulation of membrane potential. Located in dendritic shaft and postsynaptic membrane. Part of AMPA glutamate receptor complex. Orthologous to human CNIH3 (cornichon family AMPA receptor auxiliary protein 3). [provided by Alliance of Genome Resources, Apr 2022]