Mouse serum amyloid A protein. Complete amino acid sequence and mRNA analysis of a new isoform.
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.
de Beer
M C
MC
Department of Medicine, University of Kentucky Medical Center, Lexington 40536.
de Beer
F C
FC
Beach
C M
CM
Carreras
I
I
Sipe
J D
JD
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide; D010450:Endopeptidases / Q000378:metabolism; D005260:Female; D015151:Immunoblotting; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D008297:Male; D008666:Metalloendopeptidases; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis*; D000685:Serum Amyloid A Protein / Q000737:chemistry* / Q000235:genetics; D014357:Trypsin / Q000378:metabolism
D010446:Peptide Fragments; D012333:RNA, Messenger; D000685:Serum Amyloid A Protein; D010450:Endopeptidases; D014357:Trypsin; D008666:Metalloendopeptidases; C039830:peptidyl-Lys metalloendopeptidase; D003488:Cyanogen Bromide