Correction

CELL BIOLOGY. For the article “Estimates of lateral and longitudinal bond energies within the microtubule lattice,” by Vincent VanBuren, David J. Odde, and Lynne Cassimeris, which appeared in issue 9, April 30, 2002, of Proc. Natl. Acad. Sci. USA (99, 6035-6040), the authors note the following. The Gibbs free energy changes referred to in the paper (ΔG, ΔG_Lat, ΔG_Long, ΔG_S, and ) should have been referred to as the standard Gibbs free energy changes, denoted with the superscript zero (i.e., ΔG⁰, , , , and , respectively), where by convention the standard condition is 1 M for the concentrations of all species. The remaining standard conditions of temperature, pressure, and pH are as given by Walker et al. (15). Also, the equations cited in the text, although thermodynamically correct, were not the ones used to perform the simulation. As a result, the first sentence of the second paragraph on page 6036 should have read: “For a reversible binding process, the equilibrium constant (K) and the standard Gibbs free energy change upon binding, ΔG⁰, are related by the equation

1A

where k_B is Boltzmann's constant...”