MOLECULAR-INTERACTIONS AND MODULARITY OF EXTRACELLULAR-MATRIX PROTEINS

During the past ten years, numerous reports have demonstrated the presence of homologous sequences repeated in different proteins. These motifs, that share common structures, are called modules. The great diversity of secreted proteins and particularly of those found in the extracellular matrix can in fact be reduced to a relatively small number of distinct modules. In this review, we underline the importance of modularity of extracellular matrix macromolecules in their supramolecular assemblies and in their physiological roles. The modules from which a particular protein is built up can be involved both in the structure of the protein, acting for example as spacers, and in functionnal aspects, leading to specific interactions with other extracellular proteins or with specific membrane receptors. The resulting interactions account for the integrity of extracellular matrices. A mutation affecting a single module can be responsible for a loss of function of the entire protein. This can lead to severe heritable disorders.