Plasmin is shown to specifically cleave vitronectin at the Arg361-Ser362 bond, 18 amino acid residues upstream from the site of the endogenous cleavage which gives rise to the two-chain form of vitronectin in plasma. The cleavage site is established using the exclusive phosphorylation of Ser378 with protein kinase A. As a result of the plasmin cleavage, the affinity between vitronectin and the type-1 inhibitor of plasminogen activator (PAI-1) is significantly reduced. This cleavage is stimulated by glycosaminoglycans, which are known to anchor vitronectin to the extracellular matrix. A mechanism is proposed through which plasmin can arrest its own production by feedback signalling, unleashing PAI-1 from the immobilized vitronectin found in the vascular subendothelium, which becomes exposed at the locus of a hemostatic event. © 1991.
Chain, D., Kreizman, T., Shapira, H., & Shaltiel, S. (1991). Plasmin cleavage of vitronectin Identification of the site and consequent attenuation in binding plasminogen activator inhibitor-1. FEBS Letters, 285(2), 251–256. https://doi.org/10.1016/0014-5793(91)80810-P