TABLE 1.

Values of equilibrium constants used in energy inventory

Symbol	Reaction	Value	Reference
Actin
Kx	Nucleotide exchange	6*	Kinosian et al. (1993)
Kp	Pi binding to filaments	1.5 μM	Carlier and Pantaloni (1988)
[MT](+)-crit	MT addition to (+)-ends	0.1 μM	Pollard et al. (2000)
[MD](−)-crit	MT addition to (−)-ends	1.7 μM	Pollard et al. (2000)
Tubulin
Kx	Nucleotide exchange	3*	Zeeberg and Caplow (1979)
Kp	Pi binding to filaments	25 mM	Carlier et al. (1988)
[MT](+)-crit	MT addition to (+)-ends	0.03 μM	Howard (2001)
[MD](−)-crit	MT addition to (−)-ends	100 μM†	Howard (2001)

^*Calculated from the ratio of measured equilibrium dissociation constants of nucleotide binding to the monomer, i.e., K_x = K_NDP/K_NTP.

^†Assumed equal to (+)-end critical concentration for tubulin·GDP.