Cohen J B, Liebermann D, Kedes L
Mol Cell Biol. 1985 Oct;5(10):2814-25. doi: 10.1128/mcb.5.10.2814-2825.1985.
In the preceding paper (J.B. Cohen, B. Hoffman-Liebermann, and L. Kedes, Mol. Cell. Biol., 5:2804-2813, 1985), we described the nucleotide sequence of ISTU4, which is a member of a new family of repetitive sequences, the Tsp family, present in a higher eucaryote, the sea urchin Strongylocentrotus purpuratus. We provided evidence that individual members of this family can act as transposable elements. Here we describe our structural analysis of the Tsp element family, which numbers about 1,000 members per haploid genome. Hybridization and nucleotide sequence analysis of several genomic Tsp clones demonstrate that structurally most Tsp elements resemble ISTU4. Tsp elements range in size up to about 1.3 kilobase pairs, have terminal domains that are conserved between the various examples studied, and contain a central portion of varying size, which may be extensively diverged. Structurally, however, the central portions are very similar and consist of several approximately 150-base-pairs-long, tandemly arranged, imperfect repeats, which are followed by a truncated repeat. The structural analysis is consistent with the possibility that the individual Tsp elements differ by multiples of these 150-base-pair repeats. One variant genomic clone has a solitary repeat and lacks the truncated repeat. The nucleotide sequences of different repeats of a single Tsp element can diverge extensively. The truncated repeat is divergent from most of the repeats, but in one case it is almost identical to a repeat of the same element. Comparison of the sequences from different elements enabled us to determine the boundaries of each structural domain and allows us to propose that each of these domains may be independent units of genetic information. Analysis of the population of Tsp-related sequences in the S. purpuratus genome by genomic blot hybridization suggests that most Tsp family members share the same overall structure. In addition, there is a structural element, about 70 base pairs long, that appears to interrupt the tandem arrangement of the 150-base-pair repeats at regular intervals.
在前一篇论文（J.B. 科恩、B. 霍夫曼 - 利伯曼和L. 凯德斯，《分子与细胞生物学》，5:2804 - 2813，1985年）中，我们描述了ISTU4的核苷酸序列，它是一个新的重复序列家族——Tsp家族的成员，存在于高等真核生物紫球海胆（Strongylocentrotus purpuratus）中。我们提供了证据表明这个家族的单个成员可以作为转座元件。在此，我们描述对Tsp元件家族的结构分析，每个单倍体基因组中该家族约有1000个成员。对几个基因组Tsp克隆的杂交和核苷酸序列分析表明，在结构上大多数Tsp元件与ISTU4相似。Tsp元件大小可达约1.3千碱基对，具有在研究的各种实例之间保守的末端结构域，并包含大小可变的中央部分，该部分可能有广泛的差异。然而，在结构上，中央部分非常相似，由几个约150碱基对长、串联排列、不完全重复序列组成，后面跟着一个截短的重复序列。结构分析与单个Tsp元件因这些150碱基对重复序列的倍数而不同的可能性一致。一个变异的基因组克隆有一个单独的重复序列且缺少截短的重复序列。单个Tsp元件的不同重复序列的核苷酸序列可能有广泛差异。截短的重复序列与大多数重复序列不同，但在一个实例中它与同一元件的一个重复序列几乎相同。对不同元件序列的比较使我们能够确定每个结构域的边界，并使我们能够提出这些结构域中的每一个可能是遗传信息的独立单元。通过基因组印迹杂交分析紫球海胆基因组中与Tsp相关的序列群体表明，大多数Tsp家族成员具有相同的总体结构。此外，有一个约70碱基对长的结构元件，似乎以规则间隔中断150碱基对重复序列的串联排列。
