Thromboplastin (tissue factor) in plasma membranes of human monocytes
| Autor: | Gustav Gaudernack, R. Holme, Hans Prydz, O. Hetland, A. B. Brovold |
|---|---|
| Rok vydání: | 1985 |
| Předmět: |
Biochemistry
Monocytes Thromboplastin chemistry.chemical_compound Tissue factor Phosphatidylcholine hemic and lymphatic diseases medicine Humans Molecular Biology Phospholipids Phosphatidylethanolamine Phospholipase C Endoplasmic reticulum Monocyte Cell Membrane Cell Biology Microscopy Electron Membrane medicine.anatomical_structure Cholesterol chemistry circulatory and respiratory physiology Subcellular Fractions Research Article |
| Zdroj: | The Biochemical journal. 228(3) |
| ISSN: | 0264-6021 |
| Popis: | The synthesis of thromboplastin, a potent trigger of blood coagulation, can be induced in human peripheral blood monocytes. Indirect evidence suggests that newly synthesized thromboplastin becomes in part available on the cell surface. We have attempted to study the localization and availability of thromboplastin more directly by isolating plasma membranes from isolated human peripheral blood monocytes. The specific activities of the plasma membrane markers increased 16-22-fold in these preparations with a recovery of about 15%. The contamination by mitochondria, lysosomes, nuclei and endoplasmic reticulum was low as estimated by marker enzymes and electron microscopy. In both unstimulated and stimulated monocytes thromboplastin was largely recovered in this plasma membrane fraction, providing direct evidence for its membrane localization. Phospholipase C (E.C. 3.1.4.3) is a potent inactivator of thromboplastin through its hydrolysis of the phospholipids necessary for thromboplastin activity [Otnaess, Prydz, Bjørklid & Berre (1972) Eur. J. Biochem. 27, 238-243]. About 70% of the total membrane thromboplastin activity was inactivated when whole cells were treated with phospholipase C and the membranes subsequently isolated. Following stimulation to induce thromboplastin synthesis, the plasma membranes showed a shift in their relative content of phosphatidylcholine and phosphatidylethanolamine consistent with a transmethylation process. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|