Because pemphigus vulgaris antigen (PVA) is homologous to desmogleins which are in desmosomes, we asked whether PVA is also localized to desmosomes. Immunogold electron microscopy was used to localize binding of PV antibodies. Rabbit antibodies raised against fusion proteins containing the extracellular portion of PVA bound to desmosomes of cultured keratinocytes. PV patient serum affinity-purified on one of these fusion proteins and injected into neonatal mice localized to separating desmosomes. These results show that PVA belongs to the desmoglein subfamily of cadherins according to sequence, localization and, presumably, function.