The central cysteine-rich (CR) domain of DnaJ proteins contains four repeats of the motif CXXCXGXG where X is any amino acid. The isolated cysteine rich domain folds in zinc dependent fashion. Each set of two repeats binds one unit of zinc. Although this domain has been implicated in substrate binding, no evidence of specific interaction between the isolated DNAJ cysteine rich domain and various hydrophobic peptides has been found [1].

1: Solution Structure of the Cysteine-rich Domain of the Escherichia coli Chaperone Protein DnaJ. Martinez-Yamout M, Legge GB, Zhang O, Wright PE, Dyson HJ; J Mol Biol 2000;300:805-818. PMID:10891270

2: The crystal structure of the yeast Hsp40 Ydj1 complexed with its peptide substrate. Li J, Qian X, Sha B; Structure. 2003;11:1475-1483. PMID:14656432