Figure 1 : (A) Crystallized HSP70 homolog Dnak from E. coli in the ADP- and peptide-bound state (PDB ID: 2KHO) (1,3). The nucleotide-binding domain (NBD) and its subdomains IA (blue), IIA (green), IB (cyan), and IIB (yellow), as well as the substrate-binding domain (SBD) are shown. The SBD is composed of a “β-sandwich” domain (orange) and an α-helical lid domain (pink). There is minimal contact between the NBD and the SBD when ADP and the substrate peptide are bound. (B) The crystal structure of the HSP70 family member yeast heat-shock protein 110 (PDB ID: 2QXL, Sse1) when ATP is bound (1,3). The colors are the same as in (A). Images from (3).