Chaperonin GroE is a 21mer protein complex composed of the subunits GroEL (14mer, 57 kDa) and GroES (7mer, 10 kDa). This complex is thought to support the protein expression and folding ability, enabling proteins to form tertiary structures upon (or immediately after) translation. Chaperonin GroE is essential to the assembly (and presumably reassembly after denaturation) of protein complexes in vivo. Both chaperonin GroEL and GroES can be used for refolding denatured proteins to recover functional activity.