Biosynthesis and secretion of functional protein S by a human megakaryoblastic cell line (MEG-01)
A human megakaryoblastic cell line (MEG-01) was investigated for the presence of protein S in culture medium and cell lysates using a specific enzyme-linked immunoassay (ELISA) and a functional assay. When 5 X 10(5) MEG-01 cells/mL was subcultured in RPMI 1640 medium with 10% fetal calf serum (FCS), the concentration of protein S antigen in the culture medium increased progressively with time from less than 8 ng/mL on day 0 to 105.6 +/- 6.0 ng/mL on day 13. Vitamin K2(1 microgram/mL) increased the production of functional protein S, whereas warfarin (1 microgram/mL) profoundly decreased the quantity and the specific activity of secreted protein S. By an indirect immunofluorescent technique, protein S antigen was detected in both MEG-01 cells and human bone marrow megakaryocytes. Immunoblot analysis of culture medium revealed two distinct bands (mol wt 84,000 and 78,000) that are identical to the doublets of purified plasma protein S. De novo synthesis of protein S was demonstrated by the presence of specific immunoprecipitable radioactivity in the medium after 5 hours of labeling of the cells with (/sup 35/S)-methionine as a 84,000 mol wt protein. Plasma protein S levels of nine patients with severe aplastic anemia were not significantly different from those of normal controls. These results suggest that megakaryocytes produce functional protein S and contain the enzymes required for the carboxylation of selected glutamic acid residues, and that protein S synthesized by megakaryocytes does not represent a main source of plasma protein S.
- Research Organization:
- Nagoya Univ. School of Medicine, Japan
- OSTI ID:
- 6279450
- Journal Information:
- Blood; (United States), Vol. 70:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PROTEINS
BIOSYNTHESIS
SECRETION
BONE MARROW CELLS
CULTURE MEDIA
ENZYME IMMUNOASSAY
ERYTHROCYTES
MAN
METHIONINE
MOLECULAR WEIGHT
PATIENTS
SULFUR 35
TRACER TECHNIQUES
VITAMIN K
AMINO ACIDS
ANIMAL CELLS
ANIMALS
AROMATICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOXYLIC ACIDS
COAGULANTS
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
DRUGS
EVEN-ODD NUCLEI
HEMATOLOGIC AGENTS
HEPARIN ANTAGONISTS
IMMUNOASSAY
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
MATERIALS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PRIMATES
QUINONES
RADIOISOTOPES
SOMATIC CELLS
SULFUR ISOTOPES
SYNTHESIS
VERTEBRATES
VITAMINS
550201* - Biochemistry- Tracer Techniques