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. 2020 Dec 22;7:622473. doi: 10.3389/fcvm.2020.622473

Figure 2.

Figure 2

Schematic overview of the PAI-1 (I) conformations as well as its interactions with plasminogen activators (PAs, E) and cofactor vitronectin. Following the formation of a non-covalent PAI-1/PA Michaelis complex (EI), the P1-P1′ bond is cleaved to generate an acyl-enzyme intermediate (E~I). From here on, the reaction proceeds through a branched pathway, resulting in either the formation of an irreversible inhibitory complex (E-I) or the generation of cleaved PAI-1 (I*) due to the hydrolysis of the acyl-enzyme intermediate. PAI-1 is shown in white; the central β-sheet A of the PAI-1 molecule in blue; the flexible reactive center loop (RCL) in red, and Arg346 and Met347 (P1-P1′) of the reactive center are indicated by magenta and cyan spheres, respectively. The PA is shown in green. Vitronectin is shown in orange. PDB structures 1DVN (45), 1DB2 (46), 5BRR (47), 3EOX (48), 1EZX (49), 1H4W (50), and 1OC0 (51) were used to generate this figure. Figure adapted from Sillen et al. (52).