Anti-IL9R antibodies are used in the immunodetection of the protein interleukin 9 receptor. In humans, the canonical protein has a reported length of 521 amino acid residues and a mass of 57.1 kDa. Its subcellular localization is in the cell membrane and is also secreted. Alternative splicing is reported to yield 3 different isoforms for this protein. A member of a the Type I cytokine receptor protein family, IL9R is known to play an important role in the immune response against parasites by acting as a receptor of IL9. Post-translational modifications have been described, including glycosylation. Synonyms for this target antigen include CD129 and IL-9 receptor.