Figure 8 summarizes the proposed interactions between γ-8 and CNIH with surface AMPAR subunits. This model is based primarily on data in which γ-8 and CNIH are expressed with the various AMPAR subunits in HEK cells, but, as we discuss below, is strongly supported by our data from CA1 pyramidal neurons. We propose based on the IKA/IGlu ratio, a sensitive assay for TARP stoichiometry (Shi et al., 2009), that all AMPAR subunit combinations presented in Figure 8 contain 4 γ-8 as shown in HEK cells for AMPAR homomers (Figures 6Aii and S7) and in neurons for AMPAR heteromers (Figures 1I and S4C). The rest of this discussion concerns the number of CNIH proteins associated with the various AMPAR subunit combinations.
