Human serum amyloid A protein. Complete amino acid sequence of a new variant

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).

Download Full-text

Mouse serum amyloid A protein. Complete amino acid sequence and mRNA analysis of a new isoform

Biochemical Journal ◽

10.1042/bj2830673 ◽

1992 ◽

Vol 283 (3) ◽

pp. 673-678 ◽

Cited By ~ 19

Author(s):

M C de Beer ◽

F C de Beer ◽

C M Beach ◽

I Carreras ◽

J D Sipe

Keyword(s):

Amino Acid ◽

Amino Acid Sequence ◽

Serum Amyloid A ◽

Density Lipoprotein ◽

Serum Amyloid ◽

Mouse Serum ◽

F1 Hybrid ◽

Complete Amino Acid Sequence ◽

Amyloid A ◽

Serum Amyloid A Protein

Four serum amyloid A protein (SAA) genes and two gene products, apo-SAA1 and apo-SAA2 were identified in BALB/c mice (type A). SJL/J mice (type B) are thought to be defective in apo-SAA2 expression. A unique variant of mouse apo-SAA was identified in SJL/J mice by isoelectric-focusing analysis of high-density lipoprotein from endotoxin-treated mice. Complete amino-acid-sequence analysis of this quantitatively major form of SJL/J apo-SAA (pI 5.9) showed it to be identical with the apo-SAA2 isoform from BALB/c mice, except for the substitution of aspartic acid for alanine at position 101. Isoform-specific analysis of mRNA from liver of BALB/c and SJL/J mice and their F1 hybrid progeny (CSJLF1/J) mice revealed further differences in the 3′ untranslated regions of the genes, not only encoding apo-SAA2 and apo-SAA pI 5.9, but also apo-SAA1. The SAA genes of SJL/J mice thus differ from BALB/c in exon 4. Additional minor isoforms corresponding to apo-SAA2 (pI 6.3) in SJL/J mice and apo-SAA (pI 5.9) in BALB/c mice were identified. We propose that, when analysing a multigene family such as SAA, thorough analysis at the protein level should complement molecular-biological approaches where the use of a too-limited repertoire of probes can obscure complexities.

Download Full-text

Aggregation of Mouse Serum Amyloid A Protein Was Promoted by Amyloid-Enhancing Factors with the More Genetically Homologous Serum Amyloid A

International Journal of Molecular Sciences ◽

10.3390/ijms22031036 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1036

Author(s):

Xuguang Lin ◽

Kenichi Watanabe ◽

Masahiro Kuragano ◽

Kiyotaka Tokuraku

Keyword(s):

Amino Acid ◽

Serum Amyloid A ◽

Animal Species ◽

Amino Acid Sequences ◽

Serum Amyloid ◽

Mouse Serum ◽

Aa Amyloidosis ◽

Basic Residue ◽

Amyloid A ◽

Serum Amyloid A Protein

Amyloid A (AA) amyloidosis is a condition in which amyloid fibrils characterized by a linear morphology and a cross-β structure accumulate and are deposited extracellularly in organs, resulting in chronic inflammatory diseases and infections. The incidence of AA amyloidosis is high in humans and several animal species. Serum amyloid A (SAA) is one of the most important precursor amyloid proteins and plays a vital step in AA amyloidosis. Amyloid enhancing factor (AEF) serves as a seed for fibril formation and shortens the onset of AA amyloidosis sharply. In this study, we examined whether AEFs extracted and purified from five animal species (camel, cat, cattle, goat, and mouse) could promote mouse SAA (mSAA) protein aggregation in vitro using quantum-dot (QD) nanoprobes to visualize the aggregation. The results showed that AEFs shortened and promoted mSAA aggregation. In addition, mouse and cat AEFs showed higher mSAA aggregation-promoting activity than the camel, cattle, and goat AEFs. Interestingly, homology analysis of SAA in these five animal species revealed a more similar amino acid sequence homology between mouse and cat than between other animal species. Furthermore, a detailed comparison of amino acid sequences suggested that it was important to mSAA aggregation-promoting activity that the 48th amino acid was a basic residue (Lys) and the 125th amino acid was an acidic residue (Asp or Glu). These data imply that AA amyloidosis exhibits higher transmission activity among animals carrying genetically homologous SAA gene, and may provide a new understanding of the pathogenesis of amyloidosis.

Download Full-text

The Revised Amino Acid Sequence of Serum Amyloid A (SAA) Protein in Mink

Scandinavian Journal of Immunology ◽

10.1111/j.1365-3083.1993.tb01686.x ◽

1993 ◽

Vol 37 (6) ◽

pp. 696-697 ◽

Cited By ~ 13

Author(s):

P. V. SYVERSEN ◽

K. SLETTEN ◽

G. MARHAUG ◽

G. HUSBY ◽

B. LIUM

Keyword(s):

Amino Acid ◽

Amino Acid Sequence ◽

Serum Amyloid A ◽

Serum Amyloid ◽

Amyloid A

Download Full-text

Production of an amino acid sequence-specific antiserum against human amyloid A (AA) and serum amyloid A (SAA) protein

Scandinavian Journal of Clinical and Laboratory Investigation ◽

10.3109/00365518709168478 ◽

1987 ◽

Vol 47 (6) ◽

pp. 619-626 ◽

Cited By ~ 8

Author(s):

Anders Grubb ◽

Helge Lofberg ◽

Hans Thysell ◽

Lennart Ljunggren ◽

Thomas Olsson ◽

...

Keyword(s):

Amino Acid ◽

Amino Acid Sequence ◽

Serum Amyloid A ◽

Serum Amyloid ◽

Specific Antiserum ◽

Amyloid A

Download Full-text

Identification of a novel serum amyloid A protein in BALB/c mice

Biochemical Journal ◽

10.1042/bj2800045 ◽

1991 ◽

Vol 280 (1) ◽

pp. 45-49 ◽

Cited By ~ 27

Author(s):

M C de Beer ◽

C M Beach ◽

S I Shedlofsky ◽

F C de Beer

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Isoelectric Focusing ◽

Serum Amyloid A ◽

Serum Amyloid ◽

The Other ◽

Amino Acid Substitutions ◽

Gene Products ◽

Amyloid A ◽

Serum Amyloid A Protein

Four serum amyloid A protein (SAA) genes and two SAA gene products, SAA1 and SAA2, were identified in BALB/c mice. Using analytical isoelectric focusing we have identified a quantitatively significant new member of the SAA family and designated it ‘SAA5’. This protein has characteristics never before described for any SAA molecule. In the highly conserved region between amino acids 33 and 44, identical in all SAAs from all species examined, SAA5 had four amino acid substitutions. In addition, the induction of SAA5 by lipopolysaccharide had different kinetics from that of the other mouse SAAs. Our data suggest that the mouse SAA gene family is more complex in composition and regulation than previously surmised.

Download Full-text