Before revision:  For kinesin-1, \mathcal{Q} \muM  is locally minimized at [ATP] \approx 200 \muM and f\approx 4 pN. Remarkably, for the mutant with a longer neck-linker this local minimum vanishes , and the energetic cost to achieve the same precision as the wild-type increases significantly , which underscores the importance of molecular structure in transport properties. For the biological motors studied here , their value of \mathcal{Q semi-optimized under the cellular condition ([ATP] \approx 1 mM, f=0-1 pN).
After revision:  For kinesin-1, \mathcal{Q} \muM is locally minimized at [ATP] \approx 200 \muM and f\approx 4 pN. Remarkably, for the mutant with a longer neck-linker this local minimum vanishes , and the energetic cost to achieve the same precision as the wild-type increases significantly , which underscores the importance of molecular structure . Transport efficiencies of the biological motors studied here , their value of \mathcal{Q semi-optimized under the cellular condition ([ATP] \approx 1 mM, f=0-1 pN).