该基因是免疫球蛋白超家族的成员，编码一种将抑制信号传递给T细胞的蛋白质。该蛋白包含一个V结构域、一个跨膜结构域和一个胞质尾。编码不同亚型的替代转录剪接变异体已经被描述。膜结合异构体作为一个由二硫键连接的同二聚体发挥作用，而可溶性异构体作为一个单体发挥作用。该基因突变与胰岛素依赖性糖尿病、格雷夫斯病、桥本甲状腺炎、腹腔疾病、系统性红斑狼疮、甲状腺相关眼眶病变和其他自身免疫性疾病有关。
This gene is a member of the immunoglobulin superfamily and encodes a protein which transmits an inhibitory signal to T cells. The protein contains a V domain, a transmembrane domain, and a cytoplasmic tail. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. The membrane-bound isoform functions as a homodimer interconnected by a disulfide bond, while the soluble isoform functions as a monomer. Mutations in this gene have been associated with insulin-dependent diabetes mellitus, Graves disease, Hashimoto thyroiditis, celiac disease, systemic lupus erythematosus, thyroid-associated orbitopathy, and other autoimmune diseases.