The role of the finger and growth factor domains in the clearance of tissue-type plasminogen activator by hepatocytes.
The relative contribution of the finger/growth factor domains of tissue-type plasminogen activator (t-PA) and of the other t-PA domains to the clearance of t-PA by hepatocytes was investigated. A recombinant finger/growth factor construct inhibited t-PA and t-PA/plasminogen activator inhibitor type-1 degradation with an IC50 of 1800 nM, whereas a t-PA mutant lacking the finger and growth factor domains inhibited degradation with an estimated IC50 of 1200 nM. In comparison the IC50 of t-PA was found to be approximately 10 nM. Clearance of t-PA by human or rat hepatoma cells was not inhibited by high concentrations of fucose (50 mM), which suggests that the fucose on Thr-61 is not involved in clearance by these cells. These results suggest that the binding of t-PA involves several low affinity binding sites located on distinct domains of the t-PA molecule.
Camani
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C
Division of Hematology, University Hospital, Lausanne, Switzerland.
Kruithof
E K
EK
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D002460:Cell Line; D005643:Fucose / Q000494:pharmacology; D006133:Growth Substances; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D016296:Mutagenesis; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D017384:Sequence Deletion; D010959:Tissue Plasminogen Activator / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
D006133:Growth Substances; D011994:Recombinant Proteins; D005643:Fucose; D010959:Tissue Plasminogen Activator