Evolution of the alpha-crystallin/small heat-shock protein family.
Evolution of the alpha-crystallin/small heat-shock protein family.
复制标题
DOI：
10.1093/oxfordjournals.molbev.a039992
复制
发表时间：
1993
影响因子：
10.7
通讯作者：
W. D. de Jong;J. Leunissen;C. Voorter
中科院分区：
文献类型：
--
作者：
W. D. de Jong;J. Leunissen;C. Voorter
α-晶体蛋白/小分子热休克蛋白家族的共同特征是存在一个90-100个残基的保守同源序列。除了脊椎动物晶状体蛋白αA和αB晶体蛋白以及普遍存在的15-30 kDa热休克蛋白外，该家族还包括两个分枝杆菌表面抗原和曼氏血吸虫的一个主要虫卵抗原。高等植物中尤其存在多种小分子热激蛋白，它们至少可分为两类细胞质蛋白和一类定位于叶绿体的蛋白。最近在晶状体外的许多组织中都发现了α-晶体蛋白，特别是α-B-晶体蛋白，在许多方面都像一个小的热休克蛋白。同源序列构成了蛋白质的C-末端的一半，可能代表了一个具有更可变的C-末端延伸的结构域。这些结构域必须负责该蛋白质家族的共同结构和功能特性。对该家族不同蛋白质的系统发育树分析和生物学特性的比较表明，该家族进化的情景如下：小的热休克蛋白家族的原始作用必须是应对应激条件对细胞完整性的破坏稳定的影响。α-晶体蛋白的结构域看起来非常稳定，这使得它既适合作为寄生虫的表面抗原，也适合作为脊椎动物的长寿命晶状体蛋白。最近的研究表明，像其他热休克蛋白一样，α-晶状体蛋白和小分子热休克蛋白作为分子伴侣发挥作用，阻止不必要的蛋白质-蛋白质相互作用，并帮助变性蛋白质的折叠。许多小的热休克蛋白在正常发育过程中有不同的表达，有很好的证据表明它们参与了细胞形态重组和退行性疾病。与α-晶状体蛋白和小分子热休克蛋白的稳定、热保护作用相结合，它们也可能参与信号转导。这些蛋白质的可逆磷酸化在这方面似乎很重要。
The common characteristic of the alpha-crystallin/small heat-shock protein family is the presence of a conserved homologous sequence of 90-100 residues. Apart from the vertebrate lens proteins--alpha A- and alpha B-crystallin--and the ubiquitous group of 15-30-kDa heat-shock proteins, this family also includes two mycobacterial surface antigens and a major egg antigen of Schistosoma mansoni. Multiple small heat-shock proteins are especially present in higher plants, where they can be distinguished in at least two classes of cytoplasmic proteins and a chloroplast-located class. The alpha-crystallins have recently been found in many tissues outside the lens, and alpha B-crystallin, in particular, behaves in many respects like a small heat-shock protein. The homologous sequences constitute the C-terminal halves of the proteins and probably represent a structural domain with a more variable C-terminal extension. These domains must be responsible for the common structural and functional properties of this protein family. Analysis of the phylogenetic tree and comparison of the biological properties of the various proteins in this family suggest the following scenario for its evolution: The primordial role of the small heat-shock protein family must have been to cope with the destabilizing effects of stressful conditions on cellular integrity. The alpha-crystallin-like domain appears to be very stable, which makes it suitable both as a surface antigen in parasitic organisms and as a long-living lens protein in vertebrates. It has recently been demonstrated that, like the other heat-shock proteins, the alpha-crystallins and small heat-shock proteins function as molecular chaperones, preventing undesired protein-protein interactions and assisting in refolding of denatured proteins. Many of the small heat-shock proteins are differentially expressed during normal development, and there is good evidence that they are involved in cytomorphological reorganizations and in degenerative diseases. In conjunction with the stabilizing, thermoprotective role of alpha-crystallins and small heat-shock proteins, they may also be involved in signal transduction. The reversible phosphorylation of these proteins appears to be important in this respect.