Densitometric analysis supports random intracellular dimerization.

The 293T cells were transfected with plasmids encoding (A) Cys1149Arg and dA1 or (B) Cys1149Arg and dA13. Cell lysates were prepared and immunoprecipitated with polyclonal anti-VWF antibody 082 (anti-VWF) or monoclonal anti-A1 antibody B710 (anti-A1). After SDS-PAGE on a 5% polyacrylamide gel and Western blotting, the bands corresponding to pro-VWF species were quantitated as described under “Materials and methods.” The ratios of the larger subunit (Cys1149Arg) to each of the smaller subunits (dA1 or dA13) are indicated. For each experiment, the value in parentheses is the ratio predicted for random dimerization, per equation 2, for immunoprecipitation with anti-A1 antibody B710 that is specific for Cys1149Arg. The observed ratios are similar to the predicted ratios.