Complexity and expression patterns of the desmosomal cadherins.

Desmosomes are intercellular junctions that contain two major kinds of transmembrane glycoproteins, desmoglein and desmocollins I and II, involved in cell-cell adhesion. Recent sequence analyses have shown that both desmosomal glycoproteins belong to the larger cadherin family of cell adhesion molecules, in which they represent two different subgroups characterized by their specific sequence and topogenesis. In analyses of cDNA sequences and Northern blot experiments we have now found that both desmoglein and desmocollins are not unique gene products but occur in different subtypes produced from different genes. Comparison of the complete amino acid sequences of type 1 and type 2 desmocollins and of two desmoglein subtypes shows considerable divergence. While the desmoglein genes can be differentially expressed in different cell types, both type 1 and type 2 desmocollins can coexist in the same cells of certain stratified epithelia as shown by in situ hybridization. We conclude that the cadherin composition of desmosomes is much more complex than assumed and can differ in the various epithelia.