Component of intercellular desmosome junctions. Involved in the interaction of plaque proteins and intermediate filaments mediating cell-cell adhesion. Coordinates the transition from proliferation to differentiation in hair follicle keratinocytes (By similarity). Three calcium ions are usually bound at the interface of each cadherin domain and rigidify the connections, imparting a strong curvature to the full-length ectodomain. Defects in Dsg4 are the cause of an autosomal recessive phenotype lanceolate hair (lah). Lah rats pups develop only a few short hairs on the head and neck which form a lance head at the tip and disappear within one month. Hair regrows again a few days later, following a 29-day cycle of external growth and loss. Almost complete pelage hair loss occurs by 18 month.