Furano A V
Section on Genomic Structure and Function, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Prog Nucleic Acid Res Mol Biol. 2000;64:255-94. doi: 10.1016/s0079-6603(00)64007-2.
Mammalian LINE-1 (L1) elements belong to the superfamily of autonomously replicating retrotransposable elements that lack the long terminal repeated (LTR) sequences typical of retroviruses and retroviral-like retrotransposons. The non-LTR superfamily is very ancient and L1-like elements are ubiquitous in nature, having been found in plants, fungi, invertebrates, and various vertebrate classes from fish to mammals. L1 elements have been replicating and evolving in mammals for at least the past 100 million years and now constitute 20% or more of some mammalian genomes. Therefore, L1 elements presumably have had a profound, perhaps defining, effect on the evolution, structure, and function of mammalian genomes. L1 elements contain regulatory signals and encode two proteins: one is an RNA-binding protein and the second one presumably functions as an integrase-replicase, because it has both endonuclease and reverse transcriptase activities. This work reviews the structure and biological properties of L1 elements, including their regulation, replication, evolution, and interaction with their mammalian hosts. Although each of these processes is incompletely understood, what is known indicates that they represent challenging and fascinating biological phenomena, the resolution of which will be essential for fully understanding the biology of mammals.
哺乳动物的长散在核元件1（L1）属于自主复制反转录转座元件超家族，这类元件缺乏逆转录病毒和逆转录病毒样反转录转座子典型的长末端重复（LTR）序列。非LTR超家族非常古老，L1样元件在自然界中普遍存在，已在植物、真菌、无脊椎动物以及从鱼类到哺乳动物的各种脊椎动物类别中被发现。在过去至少1亿年里，L1元件一直在哺乳动物中复制和进化，现在在某些哺乳动物基因组中占比达20%或更多。因此，L1元件可能对哺乳动物基因组的进化、结构和功能产生了深远的，甚至可能是决定性的影响。L1元件包含调控信号并编码两种蛋白质：一种是RNA结合蛋白，另一种可能作为整合酶-复制酶发挥作用，因为它具有内切核酸酶和逆转录酶活性。本文综述了L1元件的结构和生物学特性，包括其调控、复制、进化以及与哺乳动物宿主的相互作用。尽管这些过程中的每一个都尚未被完全理解，但已知的信息表明它们代表了具有挑战性且引人入胜的生物学现象，解决这些问题对于全面理解哺乳动物生物学至关重要。
