PMEL and melanoma: To isolate a ligand-bound complex, we utilized an affinity-matured TCR-αβ (GPa3b17) (Liddy, 2013) being developed for immunotherapy, i.e., ImmTACs (Liddy et al., 2012), which binds with high affinity (KD = 13 pM) to the melanoma-derived gp100 antigenic peptide (YLEPGPVTV) in complex with the most prevalent human leukocyte antigen (HLA), HLA-A∗02:01 (HLA-A2).