Does not influence ATP binding or hydrolysis nor ADP release. Exerts influence on the interaction of DnaK with substrates; in the presence of DafA, DnaJ inhibits substrate binding, and substrate already bound to DnaK is displaced by DnaJ and DafA. Forms a heterononamer with DnaJ and DafA in the resting state. Three copies of each protein are present in the complex. Belongs to the DnaJ family.