Sagara Y, Sawae H, Kimura A, Sagara-Nakano Y, Morohashi K, Miyoshi K, Horiuchi T
Laboratory of Microbiology, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka.
J Biochem. 1990 Jan;107(1):77-83. doi: 10.1093/oxfordjournals.jbchem.a123015.
The gene structure of bovine adrenodoxin (Ad), a component of the steroid hydroxylating system in adrenal cortex mitochondria, was determined. This gene seems to be a single copy, but contains a pseudo exon in addition to the genuine gene region. The gene region for the active Ad is divided into 4 exons by 3 introns, and spans at least 27 kb. All the splice donor and acceptor sites follow the GT/AG rule. The transcription initiation site was determined by primer extension analysis, and putative TATA and GC boxes are present in the 5'-flanking region. A 12 base sequence, CCAGGGCCAGGG, is present 95 bases upstream from the transcription initiation site. A similar sequence was also found in the 5'-flanking regions of all genes for the steroid hydroxylating cytochromes P-450: P-450(SCC), P-450(11 beta), P-450(17 alpha), and P-450(C21), in the adrenal cortex. The consensus sequence for these five sequences is CGCAGGGCCATGGGA. The pseudo exon, exon 1', was present about 0.5 kb upstream from exon 1. It encodes the prepeptide region of the minor type Ad mRNA, but has a stop codon (TAA) in the frame. A TATA-box-like sequence and a CAAT-box-like sequence are also present in the 5'-flanking region of exon 1'. The GC content of exon 1 was over 80%, whereas for each of the other four exons, including exon 1', it was about 40%. Our observations suggest that exon 1, which encodes the prepeptide region of the major type Ad mRNA, has intruded into the region between exon 1' and exon 2.
确定了牛肾上腺皮质线粒体类固醇羟化系统的一个组分——牛肾上腺皮质铁氧化还原蛋白（Ad）的基因结构。该基因似乎是单拷贝的，但除了真正的基因区域外还包含一个假外显子。活性Ad的基因区域被3个内含子分隔为4个外显子，跨度至少为27 kb。所有剪接供体和受体位点均遵循GT/AG规则。通过引物延伸分析确定了转录起始位点，并且在5'-侧翼区域存在推定的TATA盒和GC盒。在转录起始位点上游95个碱基处存在一个12碱基序列CCAGGGCCAGGG。在肾上腺皮质中，类固醇羟化细胞色素P-450的所有基因（P-450(SCC)、P-450(11β)、P-450(17α)和P-450(C21)）的5'-侧翼区域也发现了类似序列。这五个序列的共有序列是CGCAGGGCCATGGGA。假外显子1'位于外显子1上游约0.5 kb处。它编码次要类型Ad mRNA的前肽区域，但在阅读框中有一个终止密码子（TAA）。在1'外显子的5'-侧翼区域也存在一个类似TATA盒的序列和一个类似CAAT盒的序列。外显子1的GC含量超过80%，而包括1'外显子在内的其他四个外显子各自的GC含量约为40%。我们的观察结果表明，编码主要类型Ad mRNA前肽区域的外显子1侵入了1'外显子和外显子2之间的区域。
