In this study, we cloned the ATP-binding cassette (ABC) subfamily G member 2 gene (Abcg2 gene; breast cancer resistance protein) from the liver of the marine pufferfish Takifugu rubripes, and examined its tissue distribution and gene structure. The full-length complementary DNA (cDNA) was 1977 base pairs (bp), comprising 15 exons in chromosome 17, and was assigned to the teleost Abcg2b paralogue. The open reading frame was 1839 bp in length, and encodes 612 amino acids constituting Walker A, Q-loop, C motif, Walker B, D-loop, and H-loop sequences in the first half and six transmembrane domains in the second half. Gene expression of Abcg2 was predominantly found in the intestines, followed by the liver and kidneys. The Kozak motif and the polyadenylation signal sequences were at respective ends of the transcript. The putative core promoter sequences including the transcription factor II B recognition elements, the TATA box, the initiator element, and the downstream core promoter element were found in the transcript and its upstream genomic DNA sequence. The hypoxia response element and the estrogen response element were located in the upstream genomic DNA sequence, suggesting that the pufferfish Abcg2 gene possesses the same regulation mechanism of transcription as the human ABCG2 gene.

中文翻译：

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海洋河豚Takifugu rubripes ATP结合盒亚家族G成员2基因的克隆和组织分布

在这项研究中，我们从海洋河豚 Takifugu rubripes 的肝脏中克隆了 ATP 结合盒 (ABC) 亚家族 G 成员 2 基因（Abcg2 基因；乳腺癌抗性蛋白），并检查了其组织分布和基因结构。全长互补 DNA (cDNA) 为 1977 个碱基对 (bp)，包含 17 号染色体中的 15 个外显子，并被分配到硬骨鱼 Abcg2b 旁系同源物。开放阅读框长 1839 bp，编码 612 个氨基酸，构成前半部分的 Walker A、Q-loop、C 基序、Walker B、D-loop 和 H-loop 序列，后半部分包含 6 个跨膜结构域. Abcg2 的基因表达主要在肠道中发现，其次是肝脏和肾脏。Kozak 基序和聚腺苷酸化信号序列分别位于转录本的末端。在转录本及其上游基因组 DNA 序列中发现了推定的核心启动子序列，包括转录因子 II B 识别元件、TATA 盒、起始元件和下游核心启动子元件。缺氧反应元件和雌激素反应元件位于上游基因组DNA序列，表明河豚Abcg2基因具有与人ABCG2基因相同的转录调控机制。