Roles of nectins in cell adhesion, migration and polarization

Nectins are Ca2+-independent immunoglobulin (Ig)like cellcell adhesion molecules, which comprise a family consisting of four members. Nectins have five activities: (1) they show Ca2+-independent cellcell adhesion activity by homo and heterotransinteractions through their extracellular regions; (2) they bind afadin, an actin filament (Factin)binding protein, through their cytoplasmic tails and are connected to the actin cytoskeleton; (3) they induce activation of Cdc42 and Rac small G proteins through their cytoplasmic tails; (4) they bind Par-3, a cell polarity protein, through their cytoplasmic tails; and (5) they heterophilically transinteract with Necls, nectinlike molecules, through their extracellular regions. Through these activities, nectins regulate a variety of cellular functions, including adhesion, migration, and polarization. Here we describe these activities and functions of nectins.