Cytokine which is involved in epithelial-mesenchymal signaling during morphogenesis of ectodermal organs. Functions as a ligand activating the DEATH-domain containing receptors EDAR and EDA2R. Isoform TAA binds only to the receptor EDAR, while isoform TA-A2 binds exclusively to the receptor EDA2R (By similarity). May also play a role in cell adhesion (PubMed:10534613). Isoform TAA binds only to the receptor EDAR, while isoform TA-A2 binds exclusively to the receptor EDA2R. Isoform TA-A2 binds exclusively to the receptor EDA2R. Homotrimer. The homotrimers may then dimerize and form higher-order oligomers. Additional isoforms seem to exist. N-glycosylated. Processing by furin produces a secreted form. Defects in Eda are the cause of the tabby phenotype in mice (the equivalent of anhidrotic ectodermal dysplasia in humans). The disease is characterized by sparse hair (atrichosis or hypotrichosis), abnormal or missing teeth and the inability to sweat due to the absence of sweat glands. Belongs to the tumor necrosis factor family.