Figure 3: 3D structure of anti-HER2 engineered antibody (sca 21 or cha 21) and B7.1 (CD80), along with the trimming steps (pyMol software). a) sca 21 (PDB code 2GJJ) contains two chains. Chain-A (red) and Chain B (blue)contain variable domains. b) Chain A was removed and Chain B was retained. c) VL & VH domains were colored pink and green, respectively. Aminoacid residues 6-116 (pink) and 143-257 (green) are VL & VH domains, respectively. d) B7.1 & CTLA-4 (PDB code 1I8L) interaction. e) CTLA-4 domains (green, C & D chains) were removed. A (blue) and B (red) chains of B7.1 contain aminoacid residues 35-242. f) Aminoacid residues 136-242 were removed and aminoacid residues 35-135 (interacting with extracellular variable-like domain) were retained.