Analysis of the interaction between desmosomal proteins: Desmoplakin and Plakophilin

Abstract

Desmosomes are intercellular junctions that anchor cytoskeletal intermediate filaments at the plasma membrane. This is achieved through a complex network of protein-protein interactions which provide a strong cell-cell adhesion and maintain the structural and functional integrity of tissues. Desmoplakin (DSP) and plakophilins (PKP) are components of these macromolecular complexes. DSP belongs to the plakin family of cytolinkers and contains in its N-terminal region a Plakin Domain –conserved in the whole family– that is formed by eight Spectrin Repeats and an SH3 domain. The Plakin Domain of DSP is important to localize DSP in the desmosomal plaque and to interact with binding partners such as PKPs, which are members of the armadillo protein family. We have designed a collection of DSP plakin domain and PKP1a fragments. The recombinants proteins were co-expressed in COS1 cells and the interactions were studied by co-immunoprecipitation. Our results suggest that the Plakin Domain of DSP harbors more than one interaction site for PKP1.