Given that destabilizing I(2) and these non-native interactions does not accelerate folding, it is concluded that the native and non-native structures present in the I(2) ensemble enable efficient folding of H2A-H2B..     ///    Mutational studies uncover non-native structure in the dimeric kinetic intermediate of the H2A-H2B heterodimer..     ///    "The contribution of helix propensity to the stability of the I(2) ensemble was assessed with a set of H2A-H2B mutants containing Ala and Gly replacements at nine sites, focusing mainly on the long, central alpha2 helix. "    ///    " The folding pathway of the histone H2A-H2B heterodimer minimally includes an on-pathway, dimeric, burst-phase intermediate, I(2). "