Lymphocyte Antigen 6H (LY6H) is a novel member of the LY6 family of glycosylphosphatidylinositol-anchored cell surface glycoproteins. LY6H contains one UPAR/Ly6 domain. Human LY6H is synthesized as a 140 amino acid precursor that contains a 25 amino acid signal sequence, 20 amino acid propeptide that is removed in the mature form, and a 90 amino acid mature chain. LY6H is highly expressed in the brain (cerebral cortex, amygdala, hippocampus and subthalamic nucleus) and in acute human leukemic cell line MOLT-3. It is also found in lower levels in testis, pancreas, small intestine and colon. It has been shown that LY6H may play a role in both the central nervous system and the immune system.