Mediates homophilic cell-cell adhesion. Present in all tissues tested, including the skin. Present in the keratinocytes and sebocytes in the skin (at protein level). Defects in Mpzl3 are the cause of rough coat (rc) phenotype, an autosomal-recessive mutation, arose spontaneously in C57BL/6J mice. Rc mice develop severe skin and hair abnormalities, including cyclic and progressive hair loss and sebaceous gland hypertrophy. Belongs to the myelin P0 protein family.