Opening image: GroEL-GroES complex from E. coli. The seven-membered GroEL ring (green) forms a hollow cylinder that is capped at one end by GroES cap (gold). The cap also contains seven subunits. The seven-fold axis of symmetry is in the vertical direction.
spin. Note the "honeycomb structure," somewhat reminescent of the space frames used in architecture and high-performance sport cars. This framework has the advantage of being light and strong, without using excessively long polypeptide chains for the quaternary structure.