Acute-phase high-density lipoprotein in the rat does not contain serum amyloid A protein.
Serum amyloid A protein (SAA) is an acute-phase apolipoprotein of high-density lipoprotein (HDL). Its N-terminal sequence is identical with that of amyloid A protein (AA), the subunit of AA amyloid fibrils. However, rats do not develop AA amyloidosis, and we report here that neither normal nor acute-phase rat HDL contains a protein corresponding to SAA of other species. mRNA coding for a sequence homologous with the C-terminal but not with the N-terminal part of human SAA is synthesized in greatly increased amounts in acute-phase rat liver. These observations indicate that the failure of rats to develop AA amyloid results from the absence of most of the AA-like part of their SAA-like protein, and that the N-terminal portion of SAA probably contains the lipid-binding sequences.
D000209:Acute-Phase Proteins; D000818:Animals; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000097:blood; D004591:Electrophoresis, Polyacrylamide Gel; D008075:Lipoproteins, HDL / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D000685:Serum Amyloid A Protein / Q000032:analysis*
D000209:Acute-Phase Proteins; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D008075:Lipoproteins, HDL; D000685:Serum Amyloid A Protein