BMC-H +Z -Z Fig. . Two dimensional free energy surfaces for photosynthetic metabolite transport across the CcmK hexamer in the synthetic carboxysome shell. Note that the two dimensions here are the position along the radial distance away from the pore center (r, upper right) and the pore normal axis (Z, lower right). The free energies are directly computed by inverting the probability distribution for metabolite centers, and are corrected for the larger surface area at increasing radius. In locations where no sampling has taken place, the probability distribution is not invertible, and so the free energy is represented as a white color.