Meiniel Olivier, Meiniel Robert, Lalloué Fabrice, Didier Robert, Jauberteau Marie-Odile, Meiniel Annie, Petit Daniel
Faculté de Médecine, INSERM/UMR 384, 28 place Henri Dunant, Clermont-Ferrand cedex, France.
J Mol Evol. 2008 Jan;66(1):1-10. doi: 10.1007/s00239-007-9055-3. Epub 2007 Nov 28.
Subcommissural organ (SCO)-spondin is a giant glycoprotein of more than 5000 amino acids found in Vertebrata, expressed in the central nervous system and constitutive of Reissner's fiber. For the first time, in situ hybridization performed on zebrafish (Danio rerio) embryos shows that the gene encoding this protein is expressed transitionally in the floor plate, the ventral midline of the neural tube, and later in the diencephalic third ventricle roof, the SCO. The modular organization of the protein in Echinodermata (Strongylocentrotus purpuratus), Urochordata (Ciona savignyi and C. intestinalis), and Vertebrata (Teleostei, Amphibia, Aves and Mammalia) is also described. As the thrombospondin type 1 repeat motifs represent an increasingly large part of the protein during Deuterostomia evolution, the duplication mechanisms leading to this complex organization are examined. The functional significance of the particularly well-preserved arrangement of the series of SCO-spondin repeat motifs and thombospondin type 1 repeats is discussed.
连合下器官（SCO）-脊髓素是一种存在于脊椎动物中的、由5000多个氨基酸组成的巨大糖蛋白，在中枢神经系统中表达，是赖氏纤维的组成成分。首次对斑马鱼（Danio rerio）胚胎进行的原位杂交显示，编码这种蛋白质的基因在神经管腹侧中线的底板中过渡性表达，随后在间脑第三脑室顶即连合下器官中表达。还描述了该蛋白在棘皮动物（紫海胆）、尾索动物（萨氏海鞘和肠海鞘）以及脊椎动物（硬骨鱼纲、两栖纲、鸟纲和哺乳纲）中的模块化结构。由于在后口动物进化过程中，血小板反应蛋白1重复基序在该蛋白中所占比例越来越大，因此研究了导致这种复杂结构的复制机制。讨论了SCO-脊髓素重复基序和血小板反应蛋白1重复序列特别保存完好的排列方式的功能意义。
