1. Characterization of a human high density lipoprotein-associated protein, NA1/NA2. Identity with SP-40,40, an inhibitor of complement-mediated cytolysis
- Author
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Borghini I, Bertha Martín, Richard James, Denis F. Hochstrasser, Daniel Pometta, and Hochstrasser Ac
- Subjects
Apolipoprotein B ,medicine.drug_class ,Immunoblotting ,Molecular Sequence Data ,Peptide ,Biology ,Monoclonal antibody ,Chromatography, Affinity ,Sequence Homology, Nucleic Acid ,medicine ,Humans ,Amino Acid Sequence ,Amino Acids ,Apolipoproteins A ,Glycoproteins ,chemistry.chemical_classification ,Immunoassay ,Molecular mass ,Apolipoprotein A-I ,Fast protein liquid chromatography ,Blood Proteins ,Molecular biology ,Amino acid ,Molecular Weight ,Cytolysis ,Clusterin ,chemistry ,Biochemistry ,Polyclonal antibodies ,biology.protein ,Chromatography, Gel ,lipids (amino acids, peptides, and proteins) ,Cardiology and Cardiovascular Medicine ,Lipoproteins, HDL ,Molecular Chaperones - Abstract
Two peptides, NA1 and NA2, which we previously suggested to be associated with high density lipoproteins (HDLs), have been purified. Polyclonal antibodies against each peptide and a monoclonal antibody against NA2 have been used to further characterize them and their association with HDL. Immunoblotting studies revealed that the peptides form a complex of molecular mass of approximately 80 kd. Agarose gel filtration showed coelution of NA1/NA2 and apolipoprotein (apo) A-I, the structural protein of HDL. This was confirmed by fast protein liquid chromatography, which further indicated that up to 60% of NA1/NA2 was located within the lower density range of the HDL spectrum. Complementary studies with anti-apo A-I immunoaffinity columns provided evidence that at least 40% of NA1/NA2 was associated with HDL, an association easily disrupted by ultracentrifugal manipulation. Finally, partial amino acid sequences showed virtually complete homology with a recently identified protein, SP-40,40, or cytolysis inhibitor. The protein is suggested to have a powerful inhibitory effect on complement-mediated cell lysis. Our results could thus furnish an explanation for the previously observed modulating influence of HDL on complement activity.
- Published
- 1991