C-reactive protein reacts with the U1 small nuclear ribonucleoprotein
- VA Medical Center, Albuquerque, NM (USA)
C-reactive protein (CRP) was found to produce a small, discrete, speckled fluorescence pattern in the nucleus of HEp-2 cells. Double staining with anti-RNP serum and CRP produced very similar staining patterns. By counterimmunoelectrophoresis CRP was bound to extractable nuclear antigens found in rabbit thymus extract. The reactive components of the extract were only partially sensitive to treatment with RNase. CRP immunoprecipitated the U1 RNA species from ({sup 32}P)labeled HeLa cells and the protein bands of the Sm/RNP complex from ({sup 35}S)-methionine-labeled HeLa cells. By blotting, CRP bound to several discrete bands in a calcium-dependent, PC-inhibitable manner. Two of the bands comigrated with the 70K protein band associated with the U1 snRNP, and its major breakdown product. Binding to these bands was inhibited by both EDTA and PC indicating that CRP binds these proteins through the PC-binding site. Binding to the 70K protein of the U1 snRNP was confirmed by reactivity with the recombinant 70K protein in a dot blot. These findings indicate the CRP binds to the U1-RNP snRNP particle. Considering the ability of CRP to inhibit antibody responses to its ligands and its ability to activate C and promote phagocytosis it is suggested that CRP may play a role in the regulation of autoantibody responses to nuclear Ag.
- OSTI ID:
- 5228719
- Journal Information:
- Journal of Immunology; (USA), Vol. 143:8; ISSN 0022-1767
- Country of Publication:
- United States
- Language:
- English
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CELL NUCLEI
ANTIGEN-ANTIBODY REACTIONS
NUCLEOPROTEINS
BIOCHEMICAL REACTION KINETICS
ELECTROPHORESIS
FLUORESCENCE
HELA CELLS
LIGANDS
MAN
METHIONINE
MOLECULAR WEIGHT
PHOSPHORUS 32
RECEPTORS
STAINS
SULFUR 35
TRACER TECHNIQUES
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
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ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPOTROPIC FACTORS
LUMINESCENCE
MAMMALS
MEMBRANE PROTEINS
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOSPHORUS ISOTOPES
PRIMATES
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550201* - Biochemistry- Tracer Techniques