Belongs to an adhesion system, probably together with the E-cadherin-catenin system, which plays a role in the organization of homotypic, interneuronal and heterotypic cell-cell adherens junctions (AJs) (By similarity). Nectin- and actin-filament-binding protein that connects nectin to the actin cytoskeleton (By similarity). May play a key role in the organization of epithelial structures of the embryonic ectoderm (PubMed:10477764). Essential for the organization of adherens junctions (By similarity). Homodimer. Interacts with F-actin, nectin and NECTIN3. Essential for the association of nectin and E-cadherin. Isoform 2/s-afadin does not interact with F-actin. Interacts with ZO-1 and occludin, but probably in an indirect manner. Interacts with RIT1, RIT2, NRXN1 and BCR (By similarity). Interacts with ADAM10; the interaction locks ADAM10 at adherens junctions following ADAM10 recruitment to adherens junctions by TSPAN33 (PubMed:30463011). Not found at cell-matrix AJs. Isoform 1 is expressed only in a restricted set of epithelial structures during early embryogenesis. Highly expressed at restricted set of epithelial structures and highly concentrated at their junctional complex regions. At 6.5 dpc, localized at the most apical regions of cell-cell adhesion sites of the entire embryonic ectoderm; not detected in the extraembryonic regions. At 7.0 dpc, expressed in the primitive streak and the migrating paraxial mesoderm. At 7.5 dpc, highly expressed at the junctional complex regions in the primitive streak region (neuroepithelium) and the neural fold/grove region, but hardly detected in other areas of the ectoderm. By 8.5 dpc, highly expressed in the tail bud, somites and the paraxial mesoderm, concentrated at the junctional complex regions in neural tube, somites and pericardioperitoneal canal. Mice show developmental defects at stages during and after gastrulation, including disorganization of the ectoderm, impaired migration of the mesoderm and loss of somites and other structures derived from both the ectoderm and mesoderm. Cell-cell adherens juntions and tight junctions are improperly organized in the ectoderm-derived cells. No redundancy exists in the function of afadin during gastrulation.