Macrophage surface component gp160: sensitivity to plasmin and other proteases.
The correlation between activation of macrophages and increased secretion of plasminogen activator suggests that macrophages are exposed to the protease plasmin. Incubation of 125I-labeled, caseinate-elicited guinea pig peritoneal macrophages with plasmin cleaves a surface protein, gp160, characterized previously by its sensitivity to trypsin. The gp160 fragments produced by plasmin (fr85 and fr71), which remain disulfide-bonded in the membrane, comigrate with the fragments produced by trypsin, indicating close or identical cleavage sites. No other detectable 125I-labeled surface component is cleaved by plasmin. Neither gp160 nor any other detectable 125I-labeled surface component was cleaved by a series of other proteases associated with inflammation including thrombin, collagenase, pancreatic elastase, leukocyte elastase, cathepsin G, and urokinase. Analysis with the use of homogeneous plasmin from guinea pig plasma shows that concentrations as low as 50 micrograms/ml cause measurable cleavage of gp160 in 30 min.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005341:Fibrinolysin / Q000494:pharmacology*; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D006168:Guinea Pigs; D006801:Humans; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism*; D010196:Pancreatic Elastase / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000494:pharmacology*; D010664:Phenylmethylsulfonyl Fluoride / Q000031:analogs & derivatives / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology
D006023:Glycoproteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011480:Protease Inhibitors; C028194:macrophage surface glycoprotein GP160; D010664:Phenylmethylsulfonyl Fluoride; C027226:(4-amidinophenyl)methanesulfonyl fluoride; D010447:Peptide Hydrolases; D010196:Pancreatic Elastase; D005341:Fibrinolysin