Desmosomes and hemidesmosomes are extremely different in their molecular composition. Most of the protein and glycoprotein components are products of members of multigene families, but show specialization for plaque formation and intermediate filament attachment. Desmosomal glycoproteins are more heterogeneous than previously suspected, with different isoforms showing tissue-specific and differentiation-related expression. Both types of junctions can be modulated in response to extracellular signals and may turn out to be involved in signal transduction.