Britten R J
Division of Biology, California Institute of Technology, 101 Dahlia Avenue, Corona del Mar, CA 92625, USA.
Proc Natl Acad Sci U S A. 1998 May 26;95(11):5906-12. doi: 10.1073/pnas.95.11.5906.
The terminal regions (last 20 kb) of Saccharomyces cerevisiae chromosomes universally contain blocks of precise sequence similarity to other chromosome terminal regions. The left and right terminal regions are distinct in the sense that the sequence similarities between them are reverse complements. Direct sequence similarity occurs between the left terminal regions and also between the right terminal regions, but not between any left ends and right ends. With minor exceptions the relationships range from 80% to 100% match within blocks. The regions of similarity are composites of familiar and unfamiliar repeated sequences as well as what could be considered "single-copy" (or better "two-copy") sequences. All terminal regions were compared with all other chromosomes, forward and reverse complement, and 768 comparisons are diagrammed. It appears there has been an extensive history of sequence exchange or copying between terminal regions. The subtelomeric sequences fall into two classes. Seventeen of the chromosome ends terminate with the Y' repeat, while 15 end with the 800-nt "X2" repeats just adjacent to the telomerase simple repeats. The just-subterminal repeats are very similar to each other except that chromosome 1 right end is more divergent.
酿酒酵母染色体的末端区域（最后20 kb）普遍含有与其他染色体末端区域精确序列相似的片段。左右末端区域是不同的，因为它们之间的序列相似性是反向互补的。直接序列相似性存在于左末端区域之间以及右末端区域之间，但不存在于任何左端和右端之间。除了少数例外，这些关系在片段内的匹配度从80%到100%不等。相似区域是由熟悉和不熟悉的重复序列以及可被视为“单拷贝”（或更好地说是“双拷贝”）序列组成的。所有末端区域都与所有其他染色体进行了正向和反向互补比较，并绘制了768个比较图。似乎在末端区域之间存在广泛的序列交换或复制历史。亚端粒序列分为两类。17个染色体末端以Y'重复序列终止，而15个末端以与端粒酶简单重复序列相邻的800 nt“X2”重复序列终止。除了1号染色体右端差异更大外，紧邻亚端粒的重复序列彼此非常相似。
