Fig. 2: Crystal structure of the HSPB7 monomeric ACD.

A The asymmetric unit of HSPB7ACDC131S contains three chains (chains A–C), packed through the neighbouring β4 and β6 + 7 strands. B The Ig-fold is very similar to that of other sHSP ACDs: it contains six β strands, with a groove between β4 and β8 and an extended “β6 + 7” strand. C Overlay of a HSPB7ACDC131S (purple) structural view with one of the closely related HSPB1 (white) reveals how the absence in HSPB7 of specific salt bridges (e.g. D129-R140 in HSPB1, highlighted here) that are conserved in the other HSPBs (Supplementary Fig. 10B) have weakened the dimer interface such that monomers are the dominant species in solution.