Helices I and II are positioned in an antiparallel mode and form one arm of the HMG box .
helices i and ii are positioned in an antiparallel mode and form one arm of the hmg box .
O O O O O O O O B-protein_substructure I-protein_substructure O O O O O O B-protein_domain_or_region I-protein_domain_or_region O