Human BTN3A3, also known as butyrophilin subfamily 3 member A3 and BTF3, is a Single-pass type I membrane protein which belongs to the immunoglobulin superfamily and BTN/MOG family. The butyrophilin (BTN) genes are a group of major histocompatibility complex (MHC)-associated genes that encode type I membrane proteins with 2 extracellular immunoglobulin domains and an intracellular B30.2 (PRYSPRY) domain. It can be detected in peripheral blood mononuclear cells, T-cells l, spleen and lymphocytes. BTN3A3 plays a role in T-cell responses in the adaptive immune response.