protein protein T-cell surface glycoprotein CD1 PR:000001838 CD1 Category=family. A protein with core architecture consisting of a signal sequence, an extracellular region with Class I Histocompatibility antigen, domains alpha 1 and alpha two (Pfam:PF00129) and an Immunoglobulin C1-set domain (Pfam:PF07654), a single-pass transmembrane region, and a very short cytoplasmic region. Forms a heterodimer with beta-2 microglobulin. protein PIRSF:PIRSF038798