Willson T A, Metcalf D, Gough N M
Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Parkville, Victoria, Australia.
Eur J Biochem. 1992 Feb 15;204(1):21-30. doi: 10.1111/j.1432-1033.1992.tb16601.x.
Leukaemia inhibitory factor (LIF) is a pleiotropic growth factor active in diverse cell systems in both the adult and the embryo. The LIF gene from a number of mammalian species is highly conserved. The ovine and porcine LIF genes were cloned, sequenced and compared to the previously published murine and human LIF gene sequences. While the coding regions of the LIF gene are highly conserved, the non-coding regions are largely non-conserved. In a region of approximately 340 bp, the 5' end of the translational initiation codon is highly conserved (84%). This region includes four conserved TATA boxes, two transcriptional start-sites identified in the murine gene and the minimal region required to function as the LIF promoter. A sequence in the murine gene adjacent to this highly conserved region which appears to contain a negative control element is, however, poorly conserved between the four species compared, except for a sequence of 16 conserved nucleotides. Within the largely non-conserved first intron, there is a block of approximately 150 nucleotides which is highly conserved between all four species (approximately 72%). However, a sequence in intron 1 of the murine LIF gene which corresponds to an alternative exon of a putative variant LIF transcript is very poorly conserved between species, with only relics of this exon evident in the other three species. A comparison of the five LIF protein sequences available (murine, rat, human, ovine and porcine) revealed that the protein displays a high degree of similarity, ranging from 74% between mouse and sheep to 92% between rat and mouse. Several large blocks of absolutely conserved amino acid sequence were identified. The ovine LIF gene was modified to allow production of recombinant ovine LIF in yeast cells, which was shown to be biologically active on murine cells.
白血病抑制因子（LIF）是一种多效生长因子，在成年和胚胎的多种细胞系统中均有活性。多种哺乳动物物种的LIF基因高度保守。克隆并测序了绵羊和猪的LIF基因，并将其与先前发表的小鼠和人类LIF基因序列进行比较。虽然LIF基因的编码区高度保守，但非编码区在很大程度上并不保守。在大约340 bp的区域内，翻译起始密码子的5'端高度保守（84%）。该区域包括四个保守的TATA框、在小鼠基因中鉴定出的两个转录起始位点以及作为LIF启动子发挥作用所需的最小区域。然而，与该高度保守区域相邻的小鼠基因中的一个序列，似乎包含一个负调控元件，在比较的四个物种之间保守性较差，除了一段16个保守核苷酸的序列。在很大程度上不保守的第一个内含子中，有一个约150个核苷酸的区域在所有四个物种之间高度保守（约72%）。然而，小鼠LIF基因内含子1中与假定的可变LIF转录本的一个可变外显子相对应的序列在物种间保守性非常差，在其他三个物种中仅能看到该外显子的残余部分。对现有的五个LIF蛋白序列（小鼠、大鼠、人类、绵羊和猪）进行比较发现，该蛋白显示出高度的相似性，小鼠和绵羊之间为74%，大鼠和小鼠之间为92%。鉴定出了几个绝对保守的氨基酸序列大片段。对绵羊LIF基因进行了修饰，以便在酵母细胞中产生重组绵羊LIF，结果表明其对小鼠细胞具有生物学活性。
