Genomic structure and chromosomal mapping of the mouse N-cadherin gene

N-cadherin is a member of the cadherin cell-cell adhesion receptor family that includes P-, E-, and R-cadherin and liver cell adhesion molecule (L-CAM). In this study, we determined the structure of the mouse N-cadherin gene by analyzing overlapping genomic clones obtained from a mouse genomic library. This gene consists of 16 exons that disperse over >200 kilobases of genomic DNA. This large size of the N-cadherin gene, compared with its cDNA (4.3 kilobases), is ascribed to the fact that the first and second introns are 34.2 kilobases and >100 kilobases long, respectively. When the N-cadherin gene was compared with that of L-CAM and P-cadherin, the exon-intron boundaries were found to be fully conserved between them, except that the P-cadherin first exon includes the first and second exons of the other two genes. Also, the second intron, which is equivalent to the first intron in P-cadherin, is exceptionally large and this structural feature is conserved in all of these genes. An interesting feature of the N-cadherin gene is that this gene has an extra 16th exon that is almost identical to the other exon, 100% in the coding region and 99% in the 3′ untranslated region in the nucleotide level. We also determined the chromosomal localization of the N-cadherin gene by interspecific backcross analysis and found that this gene is localized in the proximal region of mouse chromosome 18. The E- and P-cadherin genes are tightly linked and located on chromosome 8 in this species. Thus, N-cadherin is unlinked to these other cadherin loci.