This gene encodes a member of the immunoglobulin superfamily, containing two Ig domains with similarity to Ig variable and Ig constant domains. The gene resides in the juxta-telomeric region of the major histocompatability class 1 locus on chromosome 6 in the seven member BTN cluster, which includes butyrophilin, and three members each of the BTN2 and BTN3 subfamilies. Alternatively spliced transcript variants have been described but their full-length nature has yet to be determined.