Illustration of rotation motions and revolution motions using Phi29 revolution motor as an example. (A) 3D structure of Phi29 dsDNA packaging motor in a side view and top view with a pRNA hexamer derived from the crystal structure , and the AFM images of the pRNA hexamer with extended loops. (B) Illustration of rotation motors like the Earth rotates around its own axis. (C) Illustration of revolution motors like the Earth revolves around the Sun without rotation. (D) Illustration of the dsDNA revolution inside the hexameric ATPase channel. Only three of the six steps are shown. (E) Illustration of the dsDNA revolution inside the dodecameric connector channel, only four of the twelve steps are shown. Neither the channel nor the dsDNA needs to rotate during the revolution through channels (for animation, see http://nanobio.uky.edu/Connector-DNA_revolution.wmv).