Betts J C, Edbrooke M R, Thakker R V, Woo P
Section of Molecular Rheumatology, MRC Clinical Research Centre, Harrow, UK.
Scand J Immunol. 1991 Oct;34(4):471-82. doi: 10.1111/j.1365-3083.1991.tb01570.x.
Serum amyloid A (SAA) proteins are a group of phylogenetically conserved acute-phase reactants. Evidence is presented here for the existence of four genetic loci for the human serum amyloid A (SAA) genes. The first locus was defined by three contiguous lambda clones spanning approximately 30 kb which contained a single SAA gene encoding apoSAA1 beta. Allelic variants were isolated at the second locus: a novel clone encoding apoSAA2 alpha was distinguished from SAA2 beta (previously known as SAAg9, Ref.1) by a His/Arg polymorphism at residue 71.SAA1 and SAA2 found in the high density lipoprotein fraction of acute-phase plasma were approximately 90% homologous at the nucleotide level. Homology in the 5' flanking regions was reflected functionally with similar transcriptional responses to inflammatory cytokines in transfected hepatoma cells. A further novel gene, SAA4, was isolated from a cosmid library and mapped 10 kb downstream of SAA2. The locus defining SAA3 has been described elsewhere. Polymorphisms were detected at both SAA1 and SAA2 loci by Southern analysis and the entire SAA region mapped to discrete fragments by pulsed field analysis. The four genes account for all the hybridizing bands present on Southern analyses in a Caucasian population.
血清淀粉样蛋白A（SAA）是一组在系统发育上保守的急性期反应物。本文提供了人类血清淀粉样蛋白A（SAA）基因存在四个基因座的证据。第一个基因座由三个连续的λ克隆定义，跨度约30 kb，其中包含一个编码载脂蛋白SAA1β的单一SAA基因。在第二个基因座分离到了等位基因变体：一个编码载脂蛋白SAA2α的新克隆与SAA2β（以前称为SAAg9，参考文献1）在第71位残基处存在His/Arg多态性。急性期血浆高密度脂蛋白部分中的SAA1和SAA2在核苷酸水平上约90%同源。5'侧翼区域的同源性在功能上表现为在转染的肝癌细胞中对炎性细胞因子有相似的转录反应。从黏粒文库中分离出另一个新基因SAA4，并将其定位在SAA2下游10 kb处。定义SAA3的基因座在其他地方已有描述。通过Southern分析在SAA1和SAA2基因座均检测到多态性，并且通过脉冲场分析将整个SAA区域定位到离散片段。这四个基因构成了高加索人群Southern分析中出现的所有杂交带。
