Formation of shorter and fewer pseudo-WPBs following expression of mutant rVWF. HEK293 cells were transiently transfected with WT rVWF or rVWF variants and immunolabeled for VWF 2 days later. (A) The Volocity program was used to determine the length of at least 450 pseudo-WPBs for WT and all 3 mutants following transfection. The graph represents the percentage of pseudo-WPBs in each category (fewer than 0.5 μm, then increasing in 0.3-μm steps to more than 1.4 μm). Minimum and maximum lengths are 0.4 to 3.6 μm for WT rVWF; 0.4 to 2.8 μm for rVWF-Cys1225Gly; 0.4 to 3.4 μm for rVWF-Cys788Arg; and 0.4 to 2.0 μm for rVWF-Arg273Trp. The average length is indicated in parentheses. Each bar represents the mean ± standard deviation of all WPBs from about 30 cells in 4 independent experiments. (B) We counted the number of pseudo-WPBs in 20 randomly chosen cells. The graph represents the percentage of cells in each category (fewer than 10; from 11 to 30; and more than 30 pseudo-WPBs per cell). Each bar represents the mean ± standard deviation of 4 independent experiments.