Sathyamurthy Aruna, Allen Mark D, Murzin Alexey G, Bycroft Mark
Medical Research Council Centre for Protein Engineering, Hills Road, Cambridge CB2 2QH, United Kingdom.
J Biol Chem. 2003 Nov 21;278(47):46968-73. doi: 10.1074/jbc.M306469200. Epub 2003 Sep 1.
Sex Comb on Midleg (SCM) belongs to the Polycomb group of proteins, which are involved in transcriptional regulation in Drosophila. It is one of the components of Polycomb repressive complex 1, a multiprotein complex of Polycomb group proteins involved in the maintenance of repression and the blocking of chromatin remodeling. SCM contains two approximately 100-residue malignant brain tumor (MBT) repeats at the N terminus. These repeats are also found in other proteins involved in transcriptional repression. Here, we report the 1.78-A crystal structure of the two MBT repeats of SCM-like 2 (SCML2), a human homologue of SCM. Each repeat consists of an extended arm and a beta-barrel core. There are significant structural similarities to the Tudor, PWWP, and chromo domains, suggesting probable evolutionary relationships and functional similarities between the MBT repeats and these domains.
中腿性梳蛋白（SCM）属于多梳蛋白家族，参与果蝇的转录调控。它是多梳抑制复合物1的组成成分之一，多梳蛋白家族的一种多蛋白复合物，参与维持基因抑制及阻止染色质重塑。SCM在N端含有两个约100个残基的恶性脑肿瘤（MBT）重复序列。这些重复序列也存在于其他参与转录抑制的蛋白质中。在此，我们报道了SCM样蛋白2（SCML2）的两个MBT重复序列的1.78埃晶体结构，SCML2是SCM的人类同源物。每个重复序列由一个延伸臂和一个β桶状核心组成。与Tudor、PWWP和染色质结构域有显著的结构相似性，表明MBT重复序列与这些结构域之间可能存在进化关系和功能相似性。
