A peak in the hexamer plots where the “neck domain” of SP-D likely appears is registered about 78% of the time  (135/172 plots) in the new 4 dodecamer dataset, and about 68% of the time (151/222 plots) in the old – four dodecamer dataset.  This particular peak shows up as a slightly lower peak when the CRD domains dont quite cover this region. In molecular models (the neck and CRD domains are currently the only molecular models that I have found, show that the CRD are sort of “floppy” and sometimes appear to cover, or partially cover the neck domain.  This arrangement is very apparent in the AFM images, and drawing the line which is to be used to plot the grayscale values of is highly dependent upon the imput of the observer.  I plotted these lines trying to pick a center portion of the hexamers not varying the plot line to include or eliminate the influence of neck domain.

peak width for the neck domain is about 5 nm, but keep in mind this peak shows up under the CRD domain(s) about 70% of the time only.