SP-40,40 is a component of plasminogen activator inhibitor-1-binding protein and stabilizes plasminogen activator inhibitor-1 activity.
A complex of plasminogen activator inhibitor-1 (PAI-1) and PAI-1-binding protein (PAI-1-BP) contained S-protein (vitronectin), PAI-1 and unidentified 40-kDa protein on SDS-PAGE under reducing conditions. By Western-blot analysis, the 40-kDa protein was identified as SP-40,40 using anti-SP-40,40 antibody. Therefore, it was thought that PAI-1-BP consisted of S-protein and SP-40,40. It is known that PAI-1 is a labile protein which becomes inactive during incubation at 37 degrees C. However, after the incubation of PAI-1 with SP-40,40 at 37 degrees C for 1 h, PAI-1 could still form a complex with tissue plasminogen activator (tPA), and it inhibited plasmin formation in the mixture of plasminogen and urine plasminogen activator (uPA). The results clearly indicated that SP-40,40 stabilized PAI-1 activity as well as S-protein did.
Choi-Miura
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Department of Physiological Chemistry, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan. nammiura@pharm.showa-u.ac.jp
D002352:Carrier Proteins / Q000302:isolation & purification / Q000378:metabolism*; D051152:Clusterin; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D017395:Plasminogen Activator Inhibitor 1 / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding
D002352:Carrier Proteins; D051152:Clusterin; D006023:Glycoproteins; D018832:Molecular Chaperones; D017395:Plasminogen Activator Inhibitor 1