Tetraspanins and intercellular interactions

The superfamily of tetraspanins comprises a group of polypeptides with four transmembrane domains that form large supramolecular structures in the pla sma membrane through their associations to multiple integral membrane prote ins. They are involved in homo- and heterotypic intercellular interactions in different processes such as hematopoiesis, lymphocyte activation, cancer metastasis, and fertilization. Intercellularly located tetraspanins regula te the juxtacrine activity of growth factors, cell fusion, and myelin forma tion. On the other hand, in motile cells they relocalize from cell-cell jun ctions to actin-based structures such as filopodia or growth cones and regu late cell motility in wound healing and angiogenesis processes.