Diagrams of VWF domain organizationshowingsegments produced for supramolecular assembly. (A) The primary structure of VWF is displayed with the major assemblies/domains labeled. Amino acid residue numbers at boundaries of segments studied herein are indicated. The VWF segments produced and analyzed in this study have been shown. All expression plasmids encoded segments beginning with D1, but, owing to furin cleavage (except in the R763G mutant), protein fragments beginning at D’ were obtained for segments extending past D2. (B) Electron micrographs of negatively stained tubular assemblies formed upon incubation of the indicated VWF segments. Scale bar is 100 nm and applies to all micrographs.