von Willebrand factor, according to the publication from which I examined the AFM images of this dimer linked HERE, is a “force-sensing” dimer in blood that under conditions of increasing hydrodynamic factors can be activated to bind platelets and collagen.  AFM images provided in the manuscript look like what is a W shaped dimer becomes a T shaped dimer with the winding up of the inner arms of the W, tightly, and and unwinding as well that adds a whopping 80nm to the length of the arms and they say that this protein can get up to 15 microns long in plasma as linear multimers they call concatemers (think twisted yarn, pulling apart lengthening, then when tension is released winding back up to a single dangling fatter arm (haha or anyone who knows the twisting of the old phone cords in to winds that unwind and wind back up..this looks similar to me — and it makes sense that a force can unwind it)  von Willegrand factor is a large glycoprotein found in plasma.

Like SP-D, which is the reason that I am looking up these AFM papers, mainly trying to apply a morphometric method to various molecules) von Willebrand factor is linked by its N terminal (what a surprise, ha ha).

One interesting thing that was mentioned was a “step growth” in multimerization, adding two molecules at a time (kind of like adding one dodecamer at a time to fuzzyballs of SP-D)

Here is the image from Muller et al, which I have cropped to show the LUT tables for the tight end ( the C terminal joining of two monomers), the base of the “Y”. In the plot luminance is the ordinate, length is the abscissa a should be derived from the red bar marker, whole molecule X factor is pixels. (Super easy to do and really nice, showing these winds, almost as if the think were really coiled up on itself like twine or for those of you who sew just thread, or for those of you who embroider or do needlepoint, just like floss). Nothing surprising there, but that is one-tight end, the tension in that molecule is almost palpable. Tomorrow the open molecule will bet measured and LUT worked up, looks like two turns already.