Associates with aggregated proteins, together with IbpB, to stabilize and protect them from irreversible denaturation and extensive proteolysis during heat shock and oxidative stress. Aggregated proteins bound to the IbpAB complex are more efficiently refolded and reactivated by the ATP-dependent chaperone systems ClpB and DnaK/DnaJ/GrpE. Its activity is ATP-independent. Monomer. Forms homomultimers of about 100-150 subunits at optimal growth temperatures. Conformation changes to monomers at high temperatures or high ionic concentrations. Belongs to the small heat shock protein (HSP20) family.