BTNL4

BTNL4 is among the least characterized members of the human butyrophilin-like group, with most knowledge derived from transcriptomic and proteomic surveys rather than functional studies. The predicted protein carries two extracellular Ig-like domains and an intracellular region typical of the family, and its mRNA is detected mainly in epithelial tissues, including the gastrointestinal tract. Genome-scale analyses associate this locus with epithelial barrier and immune homeostasis programs, while related butyrophilin-like molecules in mice regulate intestinal γδ T cells. Defining the receptors and physiological roles of BTNL4 remains an open task for the field.