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. Cpn60a2 (AT5G18820) is one of putative Cpn60a subunit with low expression level in chloroplasts and is essential for embryo development.
