Reduced expression of Shank3 in Shank3 -deficient mice. (A) Targeting strategy. Top: The genomic structure of Shank3 is shown. The position of the 22t and 32t transcripts are also shown, as is the epitope for antibody N69/46. Bottom: The location of the loxP sites introduced for targeting are shown before and after the activity of the recombinase. The green bar in the wild-type allele indicates the FRT site remaining after deletion of the selection cassette. (B) Expression of Shank3 mRNA. Brain-derived mRNA from wild-type, heterozygous and knockout mice were subjected to quantitative polymerase chain reaction (qPCR) assay for Shank3 mRNA using probes across exons 6 and 7 with normalization against reference genes. (C) Expression of Shank3 in postsynaptic density (PSD) fractions. PSD fractions from wild-type, heterozygous and knockout mice were subjected to immunoblotting with antibody N69/46 to Shank3. The migration of molecular weight markers is shown on the left (in kilodaltons) and an immunoblot for βIII-tubulin as a loading control is shown below. WT, wild-type mice; Het, Shank3 heterozygous mice; KO, homozygous knockout mice. *P < 0.0003.