HDJ1, human recombinant

Hsp40/Hdj1 is a cytosolic co-chaperone belonging to the class DnaJ, named after its homolog in E. coli. Hsp40 functions in protein folding by binding nascent peptides and unfolded substrates and facilitating substrate interaction with Hsp70. Binding of Hsp40 to Hsp70 increases Hsp70 ATP hydrolysis and substrate binding, which is reversed by the action of nucleotide exchange factors (GrpE in E. coli). Repeated cycles of Hsp40/Hsp70 peptide binding and ATP hydrolysis prevent premature folding and aggregation, promoting protein maturation throughout the cell.