Serpins Identified as Cell Gowth Inhibitors in Human Plasma

摘要

We have identified a new factor,CFX,in human serum and plasma that inhibits the growth of cultured human and mouse cell lines.CFX was determined to be a negatively charged, hydrophobic glycoprotein,with a native molecular weight of 110-120 kDa and a minimal active subunit of 55 kDa.It is precipitated by 60% ammonium sulfate and is resistant to heat treatment at 100 deg C for 30 min.CFX was purified from human plasma to a single band on a gel which retained the cell growth inhibitory activity.Amino acid sequence analysis of the CFX band revealed sequences from four human glycoproteins, #alpha#1-antichymotrypsin,C1-esterade inhibitor, #alpha#1-antitrypsin,and #alpha#2-antiplasmin,all members of the superfamily of serpins.Of the four,C1-esterase inhibitor was shown to be the most potent cell growth inhibitor.These results suggest that serpins may play a cell growth inhibitory role in vivo,in addition to their role as protease inhibitors.