The Complete Amino‐Acid Sequence of Non‐Immunolobulin Amyloid Fibril Protein AS in Rheumatoid Arthritis

Abstract

The primary structure of a non-immunoglobulin amyloid protein AS has been determined.The protein was found to consist of 76 amino acid residues corresponding to a molecular weight of 9145. The sequence analysis showed clearly that the protein was homogeneous. A characteristic distribution of hydrophobic amino acids was observed and suggested as being of importance for the ability of this protein to form fibrils. A comparison of the protein with other amyloid protein AS showed a high degree of variability, particularly in the carboxyl-terminal region.

A Serum Component Related to Nonimmunoglobulin Amyloid Protein AS, a Possible Precursor of the Fibrils

“…Levin et al (10) suggested that protein AS is a fragment of a larger protein, since the N-terminal part of the protein in their experiments seemed to be heterogenous. We have, however, found only one amino acid, arginine, in the N-terminal position of protein AS of a secondary amyloid previously described (8,20). However, this doegs not rule out the hypothesis that protein AS is a fragment, a degradation product or a subunit of protein ASC.…”

“…The molecular weight of protein ASC (100,000) is far higher than that of protein AS (9,145) as determined by the total amino acid sequence (20). Levin et al (10) suggested that protein AS is a fragment of a larger protein, since the N-terminal part of the protein in their experiments seemed to be heterogenous.…”

“…No precipitation was observed when the supernate was tested against a polyspecific antiserum to human immunoglobulins (anti-F (ab')s2). DISCUSSION The nonimmunoglobulin amyloid protein AS with the reported molecular weight of 7,000-9,000 daltons (10,19,20) corresponding to 76 amino acids (20) is shown to be an integral part of the amyloid substance in secondary amyloidosis (8,10,19). In addition, we have recently demonstrated the presence of protein AS in amyloid preparations derived from patients with primary amyloidosis as well as amyloidosis associated with myelomatosis or macroglobulinemia (9,12).…”

Primary structure of duck amyloid protein A The form deposited in tissues may be identical to its serum precursor

“…Hyphens denote gaps to optimize homology; <Q symbolizes a pyrollidone carboxyl residue. An asterisk indicates the C-terminus of the deposited fibrillar form in man [19,20]. Sequences have been determined on the protein unless noted otherwise.…”

Immunohistochemical identification and crossreactions of amyloid-A fibril protein in man and eleven other species

“…In certain species, it is either genetically determined or an idiopathic variety (Benditt and Eriksen, 1973; for review, see Glenner, 1980). Protein AA has been identified in various species including man (Benditt and Eriksen, 1973;Ein, Kimura, Terry, Magnotta and Glenner, 1972;Levin, Franklin and Frangione, 1972;Sletten and Husby, 1974), monkey (Benditt and Eriksen, 1973;Doepel, Glorioso, Newcomer, Skinner and Abrams, 1981;Hermodson, Kuhn, Walsh, Neurath, Eriksen and Benditt, 1972), mouse (Eriksen, Ericsson, Pearsall, Lagunoff and Benditt, 1976;Skinner, Shirahama, *8bbreuiatzons: AA :…”