Butyrophilin 2A1 (BTN2A1) is an approximately widely expressed and variably glycosylated type I transmembrane glycoprotein. Mature human Butyrophilin 2A1 consisits of a 220 amino acid (aa) extracellular domain with two immunoglobulin-like domains, a 21 aa transmembrane segment, and a 258 aa cytoplasmic domain. Alternative splicing generates additional isoforms of human Butyrophilin 2A1 that lack the first Ig like domain or transmembrane segment as well as isoforms with substitutions and deletions in the cytoplasmic region. BTN2A1 is widely expressed including on colonic epithelial cells, on immune cells, and in milk fat globules. It binds to the C-type lectin DCSIGN on monocytederived dendritic cells, and this interaction can be blocked by soluble gp130 from HIV. The polymorphism of BTN2A1 has been associated with metabolic syndrome, type II diabetes mellitus, chronic kidney disease, and hypertension.