Sum of trans - and cis -FAB concentrations in arm I (grey) and arm II (black) during initial forward transport and its subsequent reversal at day 24, with dots surrounded by error bars representing concentrations measured by 1 H NMR, and solid lines showing the predictions of our model (Supplementary Section 10 ). The distinct stages studied are labelled i–v atop a ; these stages are also shown in b and c stacked below the cartoons shown in a and in the time course shown in d. i, the initial equilibrium state of the experiment; ii, shortly after starting forward transport; iii, at the steady state of forward transport (day 24); iv, shortly after reversing the transport direction by changing which arm was illuminated by which wavelength of light and v, at the steady state of reverse transport (day 44).
