Serum amyloid A protein (SAA), an acute-phase reactant and apolipoprotein of high-density lipoprotein, is a polymorphic protein with six reported isoforms. These are the products of three genes, i.e., cDNA pA1, cDNA pSAA82 and genomic DNA SAAg9, the last two being allelic variants at a single locus. We have identified an individual with additional novel SAA isoforms on isoelectric-focusing analysis. By using 3-bromo-3-methyl-2-(2′-nitrophenylsulphenyl)-indolenine (BNPS-skatole) cleavage of the protein at tryptophan residues we obtained the complete amino acid sequence of a novel isoform. Additional cleavage by endoproteinase Asp-N allowed verification of the tryptophan residues and complete amino acid sequence of both isoforms. The suitability of this approach to the rapid sequencing of SAA was demonstrated. Sequence analysis and quantification suggest that these isoforms are the result of the first confirmed allelic variation at the SAA1 locus. We designate the protein products of this allele SAA1 beta (pI 6.1) and SAA1 beta des-Arg (pI 5.6).
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March 1992
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Research Article|
March 01 1992
Human serum amyloid A protein. Complete amino acid sequence of a new variant
C M Beach;
C M Beach
*Department of Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536-0084, U.S.A.
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M C De Beer;
M C De Beer
†Department of Medicine, University of Kentucky College of Medicine, Lexington, KY 40536-0084, U.S.A.
‡VA Medical Center, Cooper Drive, Lexington, KY 40511, U.S.A.
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J D Sipe;
J D Sipe
§Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, U.S.A.
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L D Loose;
L D Loose
∥Central Research Division, Pfizer Inc., Groton, CT 06340, U.S.A.
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F C De Beer
F C De Beer
†Department of Medicine, University of Kentucky College of Medicine, Lexington, KY 40536-0084, U.S.A.
‡VA Medical Center, Cooper Drive, Lexington, KY 40511, U.S.A.
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1992 The Biochemical Society, London
1992
Biochem J (1992) 282 (2): 615–620.
Citation
C M Beach, M C De Beer, J D Sipe, L D Loose, F C De Beer; Human serum amyloid A protein. Complete amino acid sequence of a new variant. Biochem J 1 March 1992; 282 (2): 615–620. doi: https://doi.org/10.1042/bj2820615
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