Centromeres

At metaphase, mammalian chromosomes possess a twofold symmetry, with the identical duplicated sister chromatids connected at a centromere, the relative po-... 

Figure 36-5. The two sister chromatids of human chromosome 12 (x 27,850). The location of the A+T-rich centromeric region connecting sister chromatids is indicated, as are two of the four telomeres residing at the very ends of the chromatids that are attached one to the other at the centromere. (Modified and reproduced, with permission, from DuPraw EJ DNA and Chromosomes. Holt, Rinehart, and Winston, 1970.)...

Repetitive-sequence DNA can be broadly classified as moderately repetitive or as highly repetitive. The highly repetitive sequences consist of 5-500 base pair lengths repeated many times in tandem. These sequences are usually clustered in centromeres and telomeres of the chromosome and are present in about 1-10 milHon copies per haploid genome. These sequences are transcriptionally inactive and may play a strucmral role in the chromosome (see Chapter 40). 

Sullivan et al Determining centromere identity cyclical stories and... 

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Funabiki H, Hagan I, Uzawa S, Yanagida M 1993 Cell cycle-dependent specific positioning and clustering of centromeres and telomeres in fission yeast. J Cell Biol 121 961-976... 

Kerrebrock AW, Moore DP, Wu JS, Orr-Weaver TL 1995 Mei-S332, a Drosophila protein required for sister-chromatid cohesion, can localize to meiotic centromere regions. Cell 83 247-256... 

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Rattner JB 1991 The structure of the mammalian centromere. Bioessays 13 51-56 Rieder CL, Cole R 1999 Chromatid cohesion during mitosis lessons from meiosis. J Cell Sci 112 2607-2613... 

Vig BK 1981 Sequence of centromere separation analysis of mitotic chromosomes in man. Hum... 

Waizenegger IC, Hauf S, Meinke A, Peters J-M 2000 Two distinct pathways remove mammalian cohesin from chromosome arms in prophase and from centromeres in anaphase. Cell 103 399—... 

V ande Woude If you over-express separin, will that begin to target the Rec8 that is at the centromeres, or is there some post-translational modification of it ... 

Nasmyth In the yeast, most of the cleavage takes place in a Polo mutant, and the centromeres go to the poles quite normally. But the chromosomes don t fully disengage. We suspect about 10% of the Sccl may not be coming off. If you make a Pdsl /Polo double mutant (which is difficult because they are almost synthetic lethal), then it looks like there isn t much anaphase at all. But these are recent, preliminary results. 

Na+/glucose cotransporter gene SGLT2 to human chromosome 16 close to the centromere. Genomics 1993, 37, 787-789. 

Le, T. T., Pham, L. T., Butchbach, M. E. et al. SMNA7, the major product of the centromeric survival motor neuron (SMN2) gene, extends survival in mice with spinal muscular atrophy and associates with full-length SMN. Hum. Mol. Genet. 14 845-857, 2005. 

Reciprocal Translocations. These can result from the exchange of chromosomal segments between two chromosomes and, depending on the position of the centromeres in the rearranged chromosomes, different configurations will result. 

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