The intracellular domain of BTN3A1 protein binds intracellular phosphoantigens. Accumulation of phosphoantigens such as isopentenyl Pyrophosphate (IPP) is a universal sign of cellular stress or infection by an intracellular bacterium. The binding of phosphoantigens to BTN3A1 leads to an allosterically mediated change in conformation of BTN3A1's extracellular domain. This changed conformation is detected by the T cell receptor on cytotoxic
gamma delta T cells, which can then kill the stressed or infected cell. == References ==