RuBP transits the fewest times within our simulations. We observe only six permeation events overall from 1.5 µs of MD simulation (Fig. ), as many RuBP molecules get trapped in the hexamer central pore (Fig. ). One such transition of RuBP through a BMC-H hexamer protein is demonstrated in SI Animation 7. The strong charge-charge interactions between the RuBP and the KIGT motif increases RuBP residence time within the BMC-H hexamer pore. While HCO3 -and 3-PGA also have substantial charge, RuBP uniquely has strong interactions on both ends of the molecule. As a result, RuBP frequently adopts conformations within the pore where the phosphates make strong contact with K36 (Fig. ), delaying RuBP transport across the hexamer protein. Our results suggest that RuBP has a substantially smaller permeability than other metabolites through the hexameric pore.