The PPP1R1B-STARD3-TCAP-PNMT-MGC9753-ERBB2-MGC14832-GRB7 locus on human chromosome 17q12 is frequently amplified in human gastric and breast cancer. We have recently identified and characterized human MGC9753 (also known as wild-type CAB2) and mouse Mgc9753. Here, we identified and characterized mouse Erbb2 gene by using bioinformatics. BLAST programs revealed that mouse AK031099 cDNA was derived from mouse Erbb2 gene. Because AK031099 cDNA showed 806 C↷A nucleotide substitution compared with mouse genome draft sequences and mouse Erbb2 ESTs, the nucleotide sequence of mouse Erbb2 cDNA was determined in silico by correcting 806 A of AK031099 cDNA to C. Nucleotide position 48-3818 of mouse Erbb2 cDNA was the coding region. Mouse Erbb2 gene, consisting of 27 exons, was located within the Ppp1r1b-Grb7 locus on the mouse chromosome 11. Mouse Erbb2 protein (1256 aa) showed 87.5% total-amino-acid identity with human ERBB2 protein, and 95.2% total-amino-acid identity with rat Erbb2 protein. Mouse Ppp1r1b-Grb7 locus and human Ppp1r1b-Grb7 locus were evolutionarily conserved in the order and the orientation of genes therein. Nucleotide and amino-acid substitution rates of Neurod2 located centromeric to the Ppp1r1b-Grb7 locus were significantly lower than others within the Ppp1r1b-Grb7 locus. This is the first report on the complete coding sequence of mouse Erbb2 gene as well as on the comprehensive comparison of Ppp1r1b-Grb7 locus within the human and mouse genomes.

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