These PAI-1 protein have a single substitution at either the P12 or P14 position on the reactive center loop facilitating a conversion of the proteins to a substrate for proteases rather than an inhibitor. Useful for mechanistic studies.
PI03 PAI-1 (Human), P12 Substrate Form
PI04 PAI-1 (Human), P14 Substrate Form
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References:

1. Lawrence, D. A. et al. (2000) J Biol Chem 275:5839-5844
2. Audenaert A. M. et al. (1994) J Biol Chem 269:19559-19564