Swapping Nucleotides, Tuning Hsp70

Molecular chaperones such as heat shock protein 70 (Hsp70) are crucial for protein folding. Crystal structures of Hsp70 in a complex with the nucleotide exchange factor (NEF) Hsp110 reported in this issue of Cell () and in Molecular Cell () provide new insights into how NEF action specifies Hsp70 cellular function.