The interaction of thrombin with platelet protease nexin

Journal Article · Sun Oct 01 00:00:00 EDT 1989 · Thrombosis Research; (USA)

DOI:https://doi.org/10.1016/0049-3848(89)90010-8· OSTI ID:5037583

Knupp, C L ^[1]

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1. East Carolina Univ. School of Medicine, Greenville, NC (USA)

Thrombin interacts with a platelet protein which is immunologically related to fibroblast protease nexin and has been termed platelet protease nexin I (PNI). Conflicting hypotheses about the relationship of the thrombin-PNI complex formation to platelet activation have been proposed. The studies presented here demonstrate that the platelet-associated and supernatant complexes with added 125I-thrombin are formed only under conditions which produce platelet activation in normal and chymotrypsin-modified platelets. The platelet-associated complex is formed prior to the appearance of complexes in supernatants. Appearance of the supernatant complex coincides with the appearance of thrombospondin in the reaction supernatants. Excess native thrombin, dansylarginine N-(3-ethyl-1,5-pentanediyl) amide or hirudin can prevent radiolabeled platelet-associated complex formation if added before 125I-thrombin. DAPA or hirudin can prevent or dissociate complex formation if added up to one minute after thrombin but not at later time points. The surface associated complex is accessible to trypsin although a portion remains with the cytoskeletal proteins when thrombin-activated platelets are solubilized with Triton X 100. The surface-associated complex formation parallels many aspects of the specific measurable thrombin binding, yet it does not appear to involve other identified surface glycoprotein thrombin receptors or substrates. Although the time course of appearance of the complexes in supernatants is consistent with other data which suggest that PNI may be released from platelet granules during platelet activation, other explanations for the appearance of PNI on the platelet surface and in supernatants during platelet activation are possible.

• OSTI ID: 5037583
• Journal Information: Thrombosis Research; (USA), Vol. 56:1; ISSN 0049-3848
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
BLOOD PLATELETS
BIOCHEMICAL REACTION KINETICS
PROTEINS
COMPLEXES
ENZYME INHIBITORS
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MAN
THROMBIN
TRACER TECHNIQUES
ANIMALS
BETA DECAY RADIOISOTOPES
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ENZYMES
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ISOTOPE APPLICATIONS
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MAMMALS
MATERIALS
NUCLEI
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PEPTIDE HYDROLASES
PRIMATES
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550201* - Biochemistry- Tracer Techniques