ropionate (AMPA) channels containing the dominant subunit GluR-B. Of the four AMPAR constituents, GluR-A to D (GluR1 to 4), which form tetrameric channels with different binary subunit combinations, GluR-B is contained in the majority of AMPARs. GluR-B is critically involved in the formation and trafficking of AMPARs, and dominates their ion conductance and gating properties [40–46]. Notably, the normally low Ca2+ permeability of AMPA channels in principal