Regulation of mouse T cell associated serine proteinase-1 (MTSP-1) by proteinase inhibitors and sulfated polysaccharides

Mouse T cell associated serine proteinase-1 (MTSP-1) is expressed by activated T cells in vitro and in vivo, stored in cytoplasmic granules and secreted upon their specific restimulation. The aim of this study was to identify those structures which may control proteolysis by MTSP-1 in vivo in the vascular and extravascular systems. Here we show, that MTSP-1 was effectively inhibited by vascular and extravascular serpins such as antithrombin III and C1-esterase inhibitor, as well as by aprotinin and α₂-macroglobulin. On the other hand, interaction of MTSP-1 with sulfated glycosaminoglycans, i.e., heparin and chondroitin sulfate, led to increased enzymatic activity and an altered fine specificity of MTSP-1 for peptide substrates. These results suggest that the level of MTSP-1 activity as well as its specificity can be regulated by constituents of the extracellular environments.