Altered PSD protein composition in the hippocampal PSD fraction of KI mice during development. A, Immunoblot analyses of PSD fractions from WT and KI mice at the respective developmental ages for the indicated proteins. The following amounts of WT and KI PSD proteins were analyzed per lane: PSD-93, 0.5 μg; SAP102, 0.5 μg; SAP97, 2 μg; GluN2A, 0.5 μg; GluN2B, 0.5 μg; GluA1, 0.5 μg; GluA2/3, 0.5 μg; and γ2/4/8, 2 μg. The arrowhead indicates the degraded bands of PSD-93. For PSD-95, 0.25 μg of WT and 0.5 μg of KI PSD proteins were analyzed for comparison on identical membrane filters and their band intensities were corrected in B. B, Quantitation of various proteins in the PSD fractions based on the results shown in A, normalized to the wild-type level at P30 (set as 100%). The histograms show the mean ± SEM (open bars, WT; filled bars, KI). Three sets of PSD fractions at various ages (P14–P65) were examined. Simple comparison of the means and SEM of WT and KI data was performed using Student’s t-test. *P < 0.05, **P < 0.005, ***P < 0.001. In the KI PSD fraction, extensively low levels of mutant PSD-95, significantly decreased levels of PSD-93, GluA1, GluA2/3, and γ2/4/8, and increased levels of SAP102 during development are observed compared to the WT mice.