In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 79, No. 18 ( 1982-09), p. 5684-5687
Abstract:
The site of synthesis of alpha 2-plasmin inhibitor (alpha 2-PI), a physiologic inhibitor of plasmin, is not known with certainty. We have studied the production and secretion of alpha 2-PI by three established human liver cell lines derived from hepatocellular carcinoma and hepatoblastoma (Hep G2, Hep 3B, and PLC/PRF/5). As measured by a specific radioimmunoassay, the titer of alpha 2-PI increased in the medium of Hep G2 and Hep 3B cells with time, but no significant amount of alpha 2-PI was found in the medium of PLC/PRF/5. There was no evidence for a significant intracellular pool of this protein. On immunodiffusion against anti-alpha 2-PI serum, alpha 2-PI secreted by Hep G2 (G2 alpha 2-PI) formed a simple precipitin line of complete identity with the alpha 2-PI present in plasma (plasma alpha 2-PI). G2 alpha 2-PI behaved similarly to plasma alpha 2-PI in Sephadex G-150 gel filtration, sucrose density-gradient centrifugation, and crossed immunoelectrophoresis. G2 alpha 2-PI inhibited plasmin activity instantaneously in a functional assay and formed a complex with plasmin demonstrable by crossed immunoelectrophoresis. De novo synthesis of alpha 2-PI was shown by the presence of specific immunoprecipitable radioactivity in the medium after 5 hr of labeling of the cells with [35S] methionine. Analysis of the immunoprecipitates by NaDodSO4/polyacrylamide gel electrophoresis showed a single peak of radioactivity corresponding to Mr 68,000. These results indicate that the liver is a site of alpha 2-PI production.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.79.18.5684
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
1982
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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