de Jong W W, Caspers G J, Leunissen J A
Department of Biochemistry, University of Nijmegen, The Netherlands.
Int J Biol Macromol. 1998 May-Jun;22(3-4):151-62. doi: 10.1016/s0141-8130(98)00013-0.
Sequences of 40 very diverse representatives of the alpha-crystallin-small heat-shock protein (alpha-Hsp) superfamily are compared. Their characteristic C-terminal 'alpha-crystallin domain' of 80-100 residues contains short consensus sequences that are highly conserved from prokaryotes to eukaryotes. There are, in addition, some positions that clearly distinguish animal from non-animal alpha-Hsps. The alpha-crystallin domain is predicted to consist of two hydrophobic beta-sheet motifs, separated by a hydrophilic region which is variable in length. Combination of a conserved alpha-crystallin domain with a variable N-terminal domain and C-terminal extension probably modulates the properties of the various alpha-Hsps as stress-protective and structural oligomeric proteins. Phylogeny reconstruction indicates that multiple alpha-Hsps were already present in the last common ancestor of pro- and eukaryotes. It is suggested that during eukaryote evolution, animal and non-animal alpha-Hsps originated from different ancestral gene copies. Repeated gene duplications gave rise to the multiple alpha-Hsps present in most organisms.
对α-晶状体蛋白-小热休克蛋白（α-Hsp）超家族的40个极具多样性的代表序列进行了比较。它们由80 - 100个残基组成的特征性C末端“α-晶状体蛋白结构域”包含短的共有序列，这些序列从原核生物到真核生物高度保守。此外，还有一些位置能清楚地区分动物和非动物α-Hsps。预计α-晶状体蛋白结构域由两个疏水β-折叠基序组成，中间由长度可变的亲水区域隔开。保守的α-晶状体蛋白结构域与可变的N末端结构域和C末端延伸的组合可能调节了各种α-Hsps作为应激保护和结构寡聚蛋白的特性。系统发育重建表明，在原核生物和真核生物的最后一个共同祖先中就已经存在多种α-Hsps。有人认为，在真核生物进化过程中，动物和非动物α-Hsps起源于不同的祖先基因拷贝。基因的重复复制产生了大多数生物体中存在的多种α-Hsps。
