EM TOMOGRAPHY OF KINETOCHORE FORMATION

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。最近的研究强调了着丝粒特异性组蛋白H3样（CENP-A）蛋白在着丝粒功能中的重要性。我们发现，果蝇CID和人类CENP-A出现在中期作为一个三维结构，缺乏组蛋白H3。 然而，CID/CENP-A和H3核小体的块线性散布在延伸的染色质纤维上，并且CID在多核小体制备物中接近H3核小体。当CID被RNAi耗尽时，它被H3取代，证明了着丝粒染色质组织的灵活性。最后，与提出H3和CID/CENP-A核小体在S期的不同时间复制的模型相反，我们表明散布的H3和CID/CENP-A染色质在人类和苍蝇的S期同时复制。我们提出CID/CENP-A和H3核小体的独特结构排列将着丝粒染色质呈现在浓缩的有丝分裂染色体的极面。 该项目产生了以下出版物：Blower MD，Sullivan BA，Karpen GH。（2002）果蝇和人类着丝粒染色质的保守组织。开发小组。2（3）：319-30。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Recent studies have highlighted the importance of centromere-specific histone H3-like (CENP-A) proteins in centromere function. We show that Drosophila CID and human CENP-A appear at metaphase as a three-dimensional structure that lacks histone H3. However, blocks of CID/CENP-A and H3 nucleosomes are linearly interspersed on extended chromatin fibers, and CID is close to H3 nucleosomes in polynucleosomal preparations. When CID is depleted by RNAi, it is replaced by H3, demonstrating flexibility of centromeric chromatin organization. Finally, contrary to models proposing that H3 and CID/CENP-A nucleosomes are replicated at different times in S phase, we show that interspersed H3 and CID/CENP-A chromatin are replicated concurrently during S phase in humans and flies. We propose that the unique structural arrangement of CID/CENP-A and H3 nucleosomes presents centromeric chromatin to the poleward face of the condensing mitotic chromosome. This project resulted in the following publication: Blower MD, Sullivan BA, Karpen GH. (2002) Conserved organization of centromeric chromatin in flies and humans. Dev Cell. 2(3): 319-30.