High molecular mass kininogen

Additional protein constituents of the intrinsic cascade include prekallikrein, an 88 kDa protein zymogen of the protease kallikrein, and high molecular mass kininogen, a 150 kDa plasma glycoprotein that serves as an accessory factor. 

The intrinsic pathway appears to be initiated when factor XII is activated by contact with surface proteins exposed at the site of damage. High molecular mass kininogen also appears to form part of this initial activating complex (Figure 12.2). 

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