Recent proteomic approaches identified further auxiliary subunits: the cornichon homologues CNIH-2 and CNIH-3, as well as the Cystine-Knot AMPAR Modulating Protein CKAMP44 [22], [23]. CKAMP44 displays a very distinct pattern of expression in the dentate gyrus of the hippocampus, while the two cornichon isoforms are expressed throughout the brain and are associated with the majority of AMPARs. Both auxiliary subunits affect the gating properties of the GluA subunits: CKAMP44 delays recovery of the receptors from desensitization, CNIH-2/3 slow deactivation and desensitization kinetics. However, whereas CKAMP44 has been implicated in hippocampal short-term plasticity, a physiological role of CNIH-2/3 remains controversial.
