COMPUTER ANALYSIS OF LOW-COMPLEXITY AMINO ACID SEQUENCES

这个项目的目标是定义，分类和分析，使用 计算分析，蛋白质序列的所有片段 低复杂度。 这些包括残基簇， 主要是一种或几种氨基酸类型，其通常含有 这些的均聚物束或镶嵌物，非周期性图案， 低周期的部分重复。这些片段的丰富程度 序列数据库已经确定，它们的性质正在 与生物学功能和蛋白质结构的证据有关， 动力学和装配。 A.方法：局部成分的不同形式定义 复杂度被用来对低复杂度进行无偏识别 片段，无论其特定的残基聚类或重复 不同严格程度的模式。 算法经过改进， (a)选择用于进一步研究的片段，以及（B）滤出 在数据库搜索之前的非信息段。 的新方法 低复杂度序列的自动分类和邻接 已经被开发出来了。 B。Ababolition和生物学特性：约15%的 蛋白质数据库中的残基是在低复杂性的片段， 通常15-50个氨基酸，并且大约55%的蛋白质含有 一个或多个这样的片段。 这一比例大幅增加 在过去的一年中，反映了更多的数据库条目， 不考虑功能而确定的基因组序列。 穿插 低复杂性序列在许多真核生物中特别丰富， 在形态发生和胚胎发育中至关重要的蛋白质， 转录调控、信号转导和细胞内 和细胞外结构的完整性和相互作用。 项目意义：该项目突出了高丰度 和低复杂性蛋白质片段的生物学重要性， 强调了对它们的分子结构知识的相对缺乏 和动态。 低复杂度片段具有明显的多态性， 非紧凑的结构和动力学，这是必要的生物 功能新的计算机方法在消除许多 序列数据库搜索和比对分析中的伪影。

The goal of this project is to define, classify and analyze, using computational analysis, all segments of protein sequences of improbably low compositional complexity. These include residue clusters of predominantly one or a few amino acid types, which commonly contain homopolymeric tracts or mosaics of these, aperiodic patterns and sections of low-period repeats. The abundance of these segments in sequence databases has been determined and their properties are being related to evidence of biological functions and protein structure, dynamics and assembly. A. Methods: Different formal definitions of local compositional complexity were used to make unbiased identification of low-complexity segments, irrespective of their specific residue clustering or repeat patterns, at different levels of stringency. Algorithms were refined to (a) select segments for further study and (b) filter out non-informative segments prior to database searches. New methods for automated classification and neighboring of low-complexity sequences have been developed. B. Abundance and biological properties: Approximately 15% of the residues in protein databases are in low-complexity segments of typically 15-50 amino acids, and approximately 55% of proteins contain one or more such segments. This fraction has increased significantly in the last year, reflecting the greater number of database entries from genomic sequences determined without regard to function. Interspersed low-complexity sequences are particularly abundant in many eukaryotic proteins crucial in morphogenesis and embryonic development, transcriptional regulation, signal transduction and aspects of cellular and extracellular structural integrity and interactions. Significance of project: The project has highlighted the high abundance and biological importance of low-complexity protein segments and emphasized the relative lack of knowledge of their molecular structure and dynamics. Low complexity segments evidently have polymorphic, non-compact structures and dynamics which are necessary for biological function. The new computer methods are valuable in eliminating many artifacts in sequence database searches and alignment analysis.