Accessibility of receptor-bound urokinase to type-1 plasminogen activator inhibitor

Journal Article · Sat Jul 01 00:00:00 EDT 1989 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.86.13.4828· OSTI ID:5228306

Cubellis, M V; Andreasen, P; Ragno, P; Mayer, M; Dano, K; Blasi, F ^[1]

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1. Univ. of Copenhagen (Denmark)

Urokinase plasminogen activator (uPA) interacts with a surface receptor and with specific inhibitors, such as plasminogen activator inhibitor type 1 (PAI-1). These interactions are mediated by two functionally independent domains of the molecule: the catalytic domain (at the carboxyl terminus) and the growth factor domain (at the amino terminus). The authors have now investigated whether PAI-1 can bind and inhibit receptor-bound uPA. Binding of {sup 125}I-labeled ATF (amino-terminal fragment of uPA) to human U937 monocyte-like cells can be competed for by uPA-PAI-1 complexes, but not by PAI-1 alone. Preformed {sup 125}I-labeled uPA-PAI-1 complexes can bind to uPA receptor with the same binding specificity as uPA. PAI-1 also binds to, and inhibits the activity of, receptor-bound uPA in U937 cells, as shown in U937 cells by a caseinolytic plaque assay. Plasminogen activator activity of these cells is dependent on exogenous uPA, is competed for by receptor-binding diisopropyl fluorophosphate-treated uPA, and is inhibited by the addition of PAI-1. In conclusion, in U937 cells the binding to the receptor does not shield uPA from the action of PAI-1. The possibility that in adherent cells a different localization of PAI-1 and uPA leads to protection of uPA from PAI-1 is to be considered.

• OSTI ID: 5228306
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (USA) Vol. 86:13; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CHEMICAL ACTIVATION
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ELECTROPHORESIS
ENZYME INHIBITORS
ENZYMES
FIBRINOLYTIC AGENTS
HEMATOLOGIC AGENTS
HYDROLASES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
LEUKOCYTES
MATERIALS
MEMBRANE PROTEINS
MEMBRANES
MONOCYTES
NONSPECIFIC PEPTIDASES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PLASMINOGEN
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
UROKINASE