Loss of neuronal dystroglycan does not prohibit formation of GABAergic PSD but leads to minor changes in GABAAR subunit clustering. A–C, Triple immunofluorescence labeling of GABAergic postsynaptic markers in pyramidal layer of hippocampus CA1 area. The DGC is largely colocalized with α2 subunit and VGAT (A; arrowheads) but also with α1 subunit and NL2 (B; arrowheads). A minority of DGC clusters is not associated with GABAergic markers (A, B; arrows). D–H, Quantification of postsynaptic GABAergic markers in CA1 pyramidal cell layer. Cluster density and size are shown for GABAAR α1 (D), α2 (F), and γ2 (H) subunits and for gephyrin (E) and NL2 (G). A decrease of α1 subunit cluster size was accompanied by an increased α2 subunit cluster density. I, Colocalization of postsynaptic GABAergic markers was analyzed in cKO and control mice. Data are the number of colocalized clusters as percentage of first mentioned marker. No significant differences in colocalization were found between genotypes. J, Clustering of synArfGEF was analyzed in CA1 pyramidal layer of DG cKO and control mice. Data points represent individual mice (for statistical tests, see Table 2). **p < 0.01. ***p < 0.001.