HUMAN NEUTROPHIL CYTOCHROME-B LIGHT CHAIN (P22-PHOX) - GENE STRUCTURE, CHROMOSOMAL LOCATION, AND MUTATIONS IN CYTOCHROME-NEGATIVE AUTOSOMAL RECESSIVE CHRONIC GRANULOMATOUS-DISEASE
HUMAN NEUTROPHIL CYTOCHROME-B LIGHT CHAIN (P22-PHOX) - GENE STRUCTURE, CHROMOSOMAL LOCATION, AND MUTATIONS IN CYTOCHROME-NEGATIVE AUTOSOMAL RECESSIVE CHRONIC GRANULOMATOUS-DISEASE
复制标题
DOI：
10.1172/jci114898
复制
发表时间：
1990-11-01
影响因子：
15.9
通讯作者：
ORKIN, SH
中科院分区：
文献类型：
--
作者：
DINAUER, MC;PIERCE, EA;ORKIN, SH
膜结合细胞色素 b 是由 91 kD 糖蛋白（重链）和 22 kD 多肽（轻链）形成的异二聚体，是负责超氧化物生成的吞噬细胞 NADPH 氧化酶的重要组成部分。慢性肉芽肿病 (CGD) 的两个亚型中不存在细胞色素 b，这是一种以缺乏氧化酶活性为特征的遗传性疾病。由 Xp21.1 中 CYBB 基因座编码的细胞色素重链基因突变，导致 CGD 的 X 连锁形式。常染色体隐性遗传 CGD 的一种罕见亚型也缺乏细胞色素 b (A-CGD)，但此前尚未发现这种遗传缺陷。为了寻找细胞色素轻链基因座 CYBA 中可能的突变，对该基因的结构进行了表征。 CYBA 基因座定位于 16q24，.apprxeq。 600 bp 开放阅读框确定由跨越 .apprxeq 的六个外显子编码。 8.5 KB。对三名无关的 A-CGD 患者进行了研究，以寻找轻链基因突变的证据。一名患者的父母是表兄弟姐妹，他是纯合子，有一个大的缺失，除了该基因的极端 5'' 编码序列之外，其余的都被删除了。另外两名患者的单核细胞 RNA Northern 印迹显示轻链转录物非常正常。通过聚合酶链反应扩增轻链转录物并测序。一名患者是开放阅读框中含有点突变的两个等位基因的复合杂合子，这两个等位基因分别预测移码和非保守氨基酸替换。第二名患者的父母是远房表兄弟姐妹，他的单碱基替换是纯合的，导致另一个非保守氨基酸变化。这些结果表明，A-CGD 可能是由编码吞噬细胞细胞色素 b 的 22-kD 轻链的基因缺陷引起的。
A membrane-bound cytochrome b, a heterodimer formed by a 91-kD glycoprotein (heavy chain) and a 22-kD polypeptide (light chain), is an essential component of the phagocyte NADPH-oxidase responsible for superoxide generation. Cytochrome b is absent in two subgroups of chronic granulomatous disease (CGD), an inherited disorder characterized by the lack of oxidase activity. Mutations in the cytochrome heavy chain gene, encoded by the CYBB locus in Xp21.1, result in the X-linked form of CGD. A rare subgroup of autosomal recessive CGD also lacks cytochrome b (A-CGD), but the genetic defect has not previously been identified. In order to search for possible mutations in the cytochrome light chain locus, CYBA, the structure of this gene was characterized. The CYBA locus was localized to 16q24, and the .apprxeq. 600-bp open reading frame determined to be encoded by six exons that span .apprxeq. 8.5 kb. Three unrelated patients with A- CGD were studied for evidence of mutations in the light chain gene. One patient, whose parents were first cousins, was homozygous for a large deletion that removed all but the extreme 5'' coding sequence of the gene. The other two patients had a grossly normal light chain transcript on Northern blot of mononuclear cell RNA. The light chain transcript was amplified by the polymerase chain reaction and sequenced. One patient was a compound heterozygote for two alleles containing point mutations in the open reading frame that predict a frame shift and a nonconservative amino acid replacement, respectively. The second patient, whose parents were second cousins, was homozygous for a different single-base substitution resulting in another nonconservative amino acid change. These results indicate that A- CGD can result from defects in the gene encoding the 22-kD light chain of the phagocyte cytochrome b.