Exon-intron organization of the human type 2 desmocollin gene (DSC2): desmocollin gene structure is closer to "classical" cadherins than to desmogleins.

The cadherins are a superfamily of calcium-dependent glycoproteins that are cell adhesion molecules. Two families of cadherins, the desmocollins (Dsc) and desmogleins (Dsg), are found only in the desmosome type of cell-cell junction. They are each present in at least three different isoforms with differing spatial and temporal distributions and are specified by two clusters of closely linked genes on human chromosome 18q12.1. The human DSC2 gene, coding for the most widely distributed form of the desmocollins, has been found to consist of more than 32 kb of DNA. By using PCR we have determined the exon-intron organization. The gene is arranged into 17 exons ranging in size from 46 to 258 bp; exon 16 is alternatively spliced, giving rise to the a and b forms of the protein. This has revealed a remarkable degree of conservation of intron position with other cadherins. The desmocollin exon-intron organization is more similar to the so-called classical cadherins than to the desmogleins, especially in the cytoplasmic domain. Intron 1 is the largest in DSC2, as it is in the desmogleins, in contrast to the classical cadherins, where intron 2 is extremely large; this latter intron is missing from the desmogleins.