This gene encodes a type I membrane glycoprotein containing two extracellular immunoglobulin domains，a transmembrane and a cytoplasmic domain. This gene is expressed by various cell types，including B cells，a subset of T cells，thymocytes，endothelial cells，and neurons. The encoded protein plays an important role in immunosuppression and regulation of anti-tumor activity. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq，Jan 2016]