Type I chaperonins are large, double ring complexes invovled in mediating the folding of unfolded proteins. In chloroplasts, chaperonin complex is designated Cpn60 complex. In Arabidopsis, two Cpn60a subunits and four Cpn60B subunits are present. Cpn60B4 (AT1G26230) is one of Cpn60B subunit and is essential for folding of the NdhH subunits of the NDH complex.
