The Grin3b and Tmem259 genes are arranged with a tail-to-tail fashion with overlapping 3' coding region of both genes. The entire Grin3b coding region and the partial 3' coding region of Tmem259 gene between the 5'- and 3'-arm in the wild-type allele was replaced by a Neo/PGK cassette. (J:185796, J:223306)