title: Familial amyloidosis in cats: Siamese and Abyssinian AA proteins differ in primary sequence and pattern of deposition.
abstract: Familial AA amyloidosis is a hereditary trait in Abyssinian cats, with the kidney as the main target organ. The amino acid sequence of the amyloid A protein of the Abyssinian cat has been described earlier. Recently, familial amyloidosis has been found in Siamese cats, with the liver as the main target organ. In the present paper, we describe the complete amino amid sequence of the major constituent protein, of two Siamese cats. Siamese hepatic protein AA showed homology with, but was different from all feline SAA and AA sequences hitherto reported. Two substitutions (46Q-R and 52A-V) from the Abyssinian protein sequence were identified, one of which (46Q-R) is a non-homologous substitution not found in mammalian SAA, but is present in two bird AA amyloid proteins. This shows the presence of an unique amyloidogenic SAA isotype in Siamese cats. Both the Siamese and the Abyssinian sequence are amyloidogenic, thus making identification of amyloidogenic residues difficult. Apart from the apparent inherent amyloidogenicity of SAA, it can not be excluded that certain amino acid substitutions could enhance its amyloidogenicity but also could contribute to tissue predilection in amyloidosis.
authors.affiliation: Institute for Animal Science and Health (ID-DLO), Lelystad, The Netherlands. t.a.niewold@id.dlo.nl
authors.forename: T A
authors.initials: TA
authors.lastname: Niewold
authors.forename: J S
authors.initials: JS
authors.lastname: van der Linde-Sipman
authors.forename: C
authors.initials: C
authors.lastname: Murphy
authors.forename: P C
authors.initials: PC
authors.lastname: Tooten
authors.forename: E
authors.initials: E
authors.lastname: Gruys
mesh_terms: D000595:Amino Acid Sequence; D000686:Amyloidosis / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*; D000818:Animals; D001053:Apolipoproteins / Q000737:chemistry* / Q000378:metabolism; D002371:Cat Diseases / Q000235:genetics* / Q000378:metabolism; D002415:Cats; D006801:Humans; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D000685:Serum Amyloid A Protein / Q000737:chemistry* / Q000378:metabolism; D013045:Species Specificity
chemical_list: D001053:Apolipoproteins; D000685:Serum Amyloid A Protein