FIGURE 6.

ABS3 is required to form the non-circulating FXI pool. Representative western blots of (A) muFXI in which alanine residues replace basic residues Arg³¹⁹, Arg³²⁴, and Arg³²⁶ or (B) huFXI in which residues 319, 324, and 326 were replaced with arginine (as in muFXI) were expressed in F11−/− mice by HTI. Seven days post-HTI, mice received infusions of normal saline (NS) and blood was collected 5 minutes later. The same animals then received infusions of heparin (Hep, 2000 U/Kg) or protamine (Pro, 40 mg/Kg), and blood was again collected 5 minutes later. (C) muFXI-HA and huFXI-HA were applied to a heparin-sepharose column and eluted with a linear sodium chloride gradient. Plasma-derived human FXI eluted at a position identical to huFXI-HA (data not shown). (Right) Western blots of elution fractions from the heparin-sepharose column, probed with an anti-FXI antibody. Note that muFXI elutes at a higher salt concentration than huFXI. Shown are representative results of studies run in triplicate