"Data_SFig10H.xlsx" contains the individual values that make up Fig. S10H, including the conversion factor from contrast to mass. 

"Corresponding_step_traces.xlsx" displays step traces that were used to do the step size to mass correlation in Fig. S10G_H. The steps are numbered in the
order of appearance in the tables of "Data_SFig10H.xlsx".
The column "selected step" indicates the step used to generate a difference image displaying the incoming or outgoing actin subunit such as in the right column
in Fig. S10G.


The folders "Single_actin_steps", "Double_actin_steps" and "Triple_actin_steps" contain the corresponding images of subunit additions to the step traces in
"Corresponding_step_traces.xlsx". The images are in txt-file format that contain the pixel values of the images arranged as arrays of contrast values. They can be
loaded as text images using ImageJ.

"Filament_tip.txt" shows the filament tip at the time of the step. "Step_differential.txt" is the difference image generated by subtracting an averaged image
represented by the plateau before the step from that after a step. A dark spot represents attachment of an actin subunit, a bright spot represents detachment of a subunit.

In order to determine a contrast value for the incoming or outgoing actin subunit the shot noise in the differentials was filtered through convolution with a 2D Gaussian kernel of 5x5 pixels size
and sigma of 1.7 pixels, which has a similar size as the point spread function of the microscope. The convolved image is saved as "Gaussian_convolution_5x5_1.7sigma.txt".
The contrast values given in "Data_SFig10H.xlsx" represent the values of the darkest pixel in the Gaussian convolution image. This way of determining the contrast was chosen,
because the slightly distorted shape of some of the point spread functions in these images prevented a reasonable fit with a 2D Gaussian or our model PSF.