Takahashi I, Nobukuni T, Ohmori H, Kobayashi M, Tanaka S, Ohshima K, Okada N, Masui T, Hashimoto K, Iwashita S
National Institute of Infectious Diseases, Tokyo 162-8640, Japan.
Gene. 1998 May 12;211(2):387-94. doi: 10.1016/s0378-1119(98)00136-x.
A novel protein, BCNT, originally isolated from bovine brain and named after Bucentaur, contains an internal portion that is translated from part of bovine LINE repetitive sequence (Bov-B LINE). Human cDNA highly homologous to the bovine bcnt (bbcnt) cDNA has been isolated but does not contain a sequence similar to the Bov-B LINE insert (Nobukuni, T., Kobayashi, M., Omori, A., Ichinose, S., Iwanaga, T., Takahashi, I., Hashimoto, K., Hattori, S., Kaibuchi, K., Miyata, Y., Masui, T., Iwashita, S., 1997. An Alu-linked repetitive sequence corresponding to 280 amino acids is expressed in a novel bovine protein, but not in its human homologue. J. Biol. Chem. 272, 2801-2807). In this study, we conducted a polymerase chain reaction analysis to investigate whether such a Bov-B LINE insert is present in bcnt orthologs in other animals and in the genomic sequence of the human BCNT (hBCNT) gene. The results indicate that the Bov-B LINE insert is present in the genomic sequences of bcnt orthologs from sheep, goats, axis deer, and mouse deer (chevrotain), that is in Ruminantia, but not in pigs or human. Analysis of the bbcnt genomic sequence around the Bov-B LINE insert revealed a large part of the inserted Bov-B LINE sequence to be included in an exon; this is followed by a 54-nucleotide sequence that is highly homologous to Bov-B LINE in the 3'-side intron. The hBCNT gene was isolated and found to consist of seven exons and six introns, among which the intron corresponding to the Bov-B LINE insertion site in the bbcnt genome is 16.5kb in length with no sequence similar to Bov-B LINE. Based on these results, it seems likely that the Bov-B LINE insert is derived from a long Bov-B LINE repetitive sequence transposed to an ancestral bcnt gene in Ruminantia and reformed as a new exon through new splicing sites in the transposed sequence.
一种最初从牛脑中分离出来并以凯旋马车（Bucentaur）命名的新型蛋白质BCNT，包含一个由牛长散在重复序列（Bov-B LINE）的一部分翻译而来的内部区域。已分离出与牛bcnt（bbcnt）cDNA高度同源的人cDNA，但其中不包含与Bov-B LINE插入序列相似的序列（Nobukuni, T., Kobayashi, M., Omori, A., Ichinose, S., Iwanaga, T., Takahashi, I., Hashimoto, K., Hattori, S., Kaibuchi, K., Miyata, Y., Masui, T., Iwashita, S., 1997. 一种与280个氨基酸相对应的Alu连接重复序列在一种新型牛蛋白质中表达，但在其人类同源物中不表达。《生物化学杂志》272, 2801 - 2807）。在本研究中，我们进行了聚合酶链反应分析，以研究在其他动物的bcnt直系同源物以及人BCNT（hBCNT）基因的基因组序列中是否存在这样的Bov-B LINE插入序列。结果表明，Bov-B LINE插入序列存在于绵羊、山羊、坡鹿和鼷鹿（麝）等反刍动物的bcnt直系同源物的基因组序列中，但不存在于猪或人的基因组序列中。对Bov-B LINE插入序列周围的bbcnt基因组序列分析表明，插入的Bov-B LINE序列的很大一部分包含在外显子中；随后是一个在3'侧翼内含子中与Bov-B LINE高度同源的54个核苷酸的序列。hBCNT基因被分离出来，发现它由7个外显子和6个内含子组成，其中与bbcnt基因组中Bov-B LINE插入位点相对应的内含子长度为16.5kb，没有与Bov-B LINE相似的序列。基于这些结果，Bov-B LINE插入序列似乎源自一个转座到反刍动物祖先bcnt基因中的长Bov-B LINE重复序列，并通过转座序列中的新剪接位点重新形成一个新的外显子。
