2G12 Structure*
Compared to Ordinary Fab Structure
  1. Intact IgG
  2. Ordinary Fab
  3. Two adjacent Fab's

  4. Morph: 2 Fab's -> 2G12   Backbones (slower)   Spacefilled (slower)
        (If the morph window is too small, resize it, then refresh/reload.)

  5. 2G12 Framework Somatic Hypermutation Details
    (1op5 3.0 Å: 1o ligand 400 Å2, 2o 300 Å2. 8-9 HBonds in each.)
        A. Framework mutations for 1OP3 (two disaccharide contacts)
        B. Crystal contacts showing oligosaccharide contacts
        1om3 (unliganded 2.2 Å)     1op3 (w/ disaccharide 1.75 Å)

  6. Proposed gp120 epitope
    • gp120 has 25 N-linked glycosylation sites.
    • "The gp120 crystallized was from the HXBc2 strain of HIV-1. It has deletions of 52 and 19 residues from the N and C termini, respectively; Gly-Ala-Gly tripeptide substitutions for 67 V1/V2 loop residues and 32 V3 loop residues; and the removal of all sugar groups beyond the linkages between the two core N-acetylglucosamine residues. This deglycosylated core gp120 is stripped of over 90% of the carbohydrate but it retains over 80% of the non-variable-loop protein. Its capacity to interact with CD4 and relevant antibodies is preserved at or near wild-type levels." (Kwong PD, et al., Nature 393:648 (1998))

* A presentation in Protein Explorer by Eric Martz to illustrate a talk on "Antibody domain exchange is an immunological solution to carbohydrate cluster recognition" (Calarese et al., Science 30:2065, 2003).