Based on limited published evidence, LY6S encodes an interferon-inducible, GPI-linked protein belonging to the lymphocyte antigen 6 family. GO annotations indicate roles in acetylcholine receptor binding and signaling at the plasma membrane. LY6S-iso1, the primary protein product, contains 9 of 10 consensus LY6 cysteine residues and is predominantly expressed in nonclassical spleen cells 1. Expression of LY6S induces shifts in inflammatory and immune response gene expression patterns, enhances viral resistance in expressing cells, and is associated with immune activation 1. LY6S shares evolutionary ancestry with the murine Ly6a subfamily gene cluster.