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. 2011 Feb 21;286(16):14282–14290. doi: 10.1074/jbc.M110.203828

FIGURE 4.

FIGURE 4.

Light scattering assays demonstrate that pB171 ParM nucleates and assembles rapidly in ATP and GTP. A and B, rapid assembly of pB171 ParM in 10 mm MgCl2-ATP (A) and 10 mm MgCl2-GTP (B) monitored by light scattering. Buffer conditions for all experiments in this figure were as follows: 100 mm KCl, 30 mm Tris-HCl, 1 mm MgCl2, 1 mm DTT. C, determination of the nucleus size and relative rates of nucleation in ATP and GTP. The log of the maximal rate of assembly (Vmax) normalized by the maximum light scattering intensity was plotted versus the log concentration of pB171 ParM. The nucleus size (n) is estimated as two times the slope of the linear fit, and the x-intercept is proportional to the square root of the nucleation rate constant times the elongation rate constant. The error bars are the S.D. of calculated values from three separate experiments. D, normalized intensity (I(t)/Imax) plotted versus normalized time (t/t½) for the highest two concentrations of pB171 ParM in ATP (dark gray) and GTP (light gray). Inset, earliest time points (triangles, ATP; circles, GTP).