Characterization of the type-1 repeat from thyroglobulin, a cysteine-rich module found in proteins from different families
Characterization of the type-1 repeat from thyroglobulin, a cysteine-rich module found in proteins from different families
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DOI：
10.1111/j.1432-1033.1996.0125h.x
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发表时间：
1996-08-15
期刊：
影响因子：
--
通讯作者：
Granier, C
中科院分区：
文献类型：
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作者：
Molina, F;Bouanani, M;Granier, C
已知人甲状腺球蛋白的氨基酸序列包含富含半胱氨酸的重复区。在这项研究中，我们报告了人甲状腺球蛋白序列中存在第11个类型-1重复，并将其描述为一个蛋白质模块。11个甲状腺球蛋白-1重复序列具有相同数量的半胱氨酸残基(6个在A型，4个在两个B型重复序列中)，半胱氨酸之间的残基数量相当恒定，并且具有保守的序列模式。通过扫描蛋白质序列数据库，发现属于六个不同家族的29种蛋白质在它们的序列中至少包含一个甚至三个甲状腺球蛋白-1重复序列。尽管该重复序列存在于许多具有结合特性的蛋白质中，但对文献中现有信息的检验表明，该重复序列在蛋白质-蛋白质相互作用中的直接作用很少被评估。对序列的距离分析表明，所有的重复序列都分离成四个在系统发育上相近的序列簇。通过序列相似性分析得到了一个一致的类型1重复序列，它由保守残基组成的中心核心，包括两个高度保守的基序QC和CWCV。来自甲状腺球蛋白的类型-1重复被发现不同于先前描述的几个富含半胱氨酸的模块，特别是来自有时被混淆的表皮生长因子样模块。因此，我们的结果提供了对重复序列的完整表征，这将有助于在新表征的蛋白质中检测这些重复序列，这是理解该模块的结构/生物学作用的必要步骤。
The amino acid sequence of human thyroglobulin is known to enclose cysteine-rich repetitive regions. In this study, we report the existence of an eleventh type-1 repeat within the human thyroglobulin sequence, and we characterize the thyroglobulin type-1 repeat as a protein module. The 11 thyroglobulin type-1 repeats possessed the same number of cysteine residues (six in type A, four in the two type B repeats), a fairly constant number of residues between cysteines and a conserved sequence pattern. By scanning protein sequence databases, 29 proteins belonging to six different families were found to enclose at least one, and up to three, thyroglobulin type-1 repeats in their sequence. Although the repeat was present in numerous proteins possessing binding properties, an examination of the information available in the literature showed that a direct role of the repeat in protein-protein interaction has rarely been assessed. A distance analysis of the sequences indicated that all repeats segregate into four clusters of phylogenically close sequences. A consensus sequence of type-1 repeats was derived from sequence similarity analysis; it comprised a central core of conserved residues including two highly conserved motifs, QC and CWCV. The type-1 repeat from thyroglobulin was found to differ from several previously described cysteine-rich modules, in particular fr om the epidermal-growth-factor-like module with which it has sometimes been confused. Therefore, our results provide a complete characterization of the repeats which will help in the detection of these repeats in newly characterized proteins, a necessary step for understanding the structural/biological role of this module.