Intercellular junctions are essential for maintenance of tissue integrity and play key roles in morphogenesis, proliferation and cell migration. Indeed desmosomes, tight junctions and cadherin-based adherens junctions are covered in pretty much every basic cell biology textbook. Less well known is the nectin—afadin system. In a Commentary on , Yoshimi Takai and Hiroyuki Nakanishi review the roles of this novel type of intercellular junction. Nectin is a Ca2+-independent, transmembrane adhesion molecule that contains three extracellular immunoglobulin-like domains, which can interact with other nectin molecules on the same cell or on a neighbouring cell. Afadin is a cytoplasmic adaptor that connects nectin to the actin cytoskeleton and might also interact with signalling molecules. The nectin—afadin system is associated with adherens junctions in fibroblasts and epithelial cells, and studies of nectin mutants and knockout work indicate that it is important for organization of both adherens junctions and tight junctions. The system also appears to play a part in organization of synapses and sertoli-cell—spermatid junctions and is thus implicated in both homotypic and heterotypic cell-cell adhesion.
