Kumaret al.,Science 367 , 1008–1014 (2020) 28 February 2020 4of7
Fig. 4. Mechanism of IgA oligomerization.Top view of (A) dimeric IgA1,
(B) tetrameric IgA2m2, and (C) pentameric IgA2m2. The SC is omitted for
clarity. (D) Magnification of the left boxed region in (C) highlighting Fc–Fc
contacts at the Ca 2 – Ca3interface.(E) Magnification of the central boxed
region in (C) highlighting the JCb-sandwich extension shown as an open
book preparation of the Fc tailpieces with repeating internal residues
labeled and side chains shown as sticks. (F) Magnification of the central
boxed region in (C) showing repeating external residues of theb-sandwich.
(G) Cross-section of the extendedb-sandwich of the pentamer with Fc5
omitted for clarity.RESEARCH | RESEARCH ARTICLE