The spectrum of anti-C2 antibody epitopes. (A) Venn diagram representing overlapping anti-C2 MAbs. The overlap pattern of 18 ellipses is derived from the competition matrix of 30 MAbs in Figure 1B. Colors depict the 5 classes of MAbs: red, group A; orange, group AB; yellow, group B; green, group BC; and blue, group C. The thick lines represent the basis set MAbs: red, ESH4 (group A); yellow, 1B5 (group B); and blue, ESH8 (group C). The white ellipse represents the epitope of BO2C11. (B) Amino acid side chains recognized by anti-C2 MAbs. The strands representing the front and back faces of the β-sandwich are shown in green and red, respectively.23 Single-letter nomenclature is used to designate amino acids. Val2223 and Lys2227 are shown as van der Waals surfaces. The group AB MAbs, I109 and BO2C11, bind to the 2 phospholipid-binding β-hairpins containing Met2199 and Leu2251, respectively. The group B MAb, 3D12, binds to Phe2196. The group BC MAbs bind to Lys2227 and possibly Val2223.
