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 greater than 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 greater than 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.