Evolution of aldolase gene in insect and vertebrate

果糖-1，6-二磷酸醛缩酶是α/β桶酶家族的成员，具有三种同工酶形式：A、B和C。果蝇醛缩酶的三种同工酶形式，α、β和γ，通过三个外显子4的交替使用从单个基因产生。将各同工酶的表达质粒转染到大肠杆菌细胞中，通过简单的方法将同工酶α和β纯化至均一，尽管同工酶γ仅部分纯化。同工酶之间的性质相似。从果蝇成虫中也获得了新类型的mRNA（命名为4-3和6-2）。4-3有两个最后的外显子4alpha和4 beta未剪接。从一级结构和酶学性质来看，4-3 mRNA的产物为同工酶α。在黑腹果蝇的组织中，已知编码外显子4 α的mRNA的产生被抑制到低水平。我们的结论是，转录编码外显子4 α和4 β，可能产生的编码框架外显子4 β，被认为是在RNA加工过程中的poly（A）信号。6-2克隆的活性位点残基（K*Q）和对FBP和FlP的醛缩酶活性存在变异，这可能为醛缩酶的分子进化提供线索。在家蚕中发现了S型和F型两种醛缩酶同工酶，并对其进行了酶学和组织表达的研究。在该器官中出现五种组分可能是由于S和F亚基形成异源四聚体所致。在实验中获得的融合蛋白和果蝇的醛缩酶同工酶可以总结如下：（a）IGS-1和4负责决定脊椎动物的醛缩酶同工酶A和C以及果蝇的醛缩酶的组织特异性。IGS-4在其他IGS中可能更具变化性。

Fructose-1,6-bisphoshate aldolase is a member of alpha / beta barrel enzyme family and has three types of the isozymes form : A,B and C.Three isozymic forms, alpha, beta and gamma, of Drosophila melanogaster aldolase are produced from a single gene by alternative usage of the triple exons 4. The expression plasmids for the respective isozymes were transfected into Escherichia coli cells, and the isozymes alpha and beta were purified to homogeneity by a simple procedure, though isozyme gamma was only partially purified. The properties were similar among isozymes. The novel-type mRNAs (named, 4-3 and 6-2) was also obtained from Drosophila adult. The 4-3 has two final exons 4alpha and 4beta unspliced. The product from 4-3 mRNA was found to be isozyme alpha from the primary structure and the enzymological properties. In tissues of D.melanogaster, the production of mRNA encoding exon4alpha is known to be restrained to a low level. We concluded that the transcript-encoding exons 4alpha and 4beta, might be produced the coding frame in exon 4beta, is recognized as poly (A) signal during RNA processing. The 6-2 clone has a variant of active site residue (K*Q) and aldolase activity for FBP and FlP.This might have a clue of molecular evolution for aldolase. In Bombyx mori, two types of aldolase isozymes, S and F,were found and studied in emzymology and tissue expressions. The occurrence of five components in the organ may be due to the formation of heterotetramers of the S and F subunits.Aldolase has four isozyme specific group sequences in internal structure. The obtained in the experiments and fusion proteins and Drosophila aldolase isozymes cab be summarised as follows : (a) IGS-1 and 4 are responsible for determining tissues-specificity of vertebrate aldolase isozyme A and C,and Drosophila aldolase. IGS-4 might be more changeable among other IGSs.