Tsutsumi K, Mukai T, Tsutsumi R, Hidaka S, Arai Y, Hori K, Ishikawa K
J Mol Biol. 1985 Jan 20;181(2):153-60. doi: 10.1016/0022-2836(85)90081-6.
The structure of the chromosomal gene encoding rat aldolase isozyme B has been elucidated by sequence analysis of cloned genomic DNA. This gene comprises about 14 X 10(3) base-pairs of DNA, and is separated into nine exons by eight intervening sequences. A presumed transcription-initiation site was assigned by S1 nuclease protection mapping, and T-A-T-A and C-C-A-A-T boxes were found to be 25 and 126 base-pairs, respectively, upstream from this initiation site. There are three characteristic sequences of 100 to 200 base-pairs within the region of 870 base-pairs flanking the 5' side of the gene. These sequences are flanked on either side by direct repeats and terminate with an A-rich stretch of nucleotides. One of them has block homology with a region in an "ID sequence", which is reported to be an element for tissue-specific gene regulation and differentiation. The other two are analogous at the sequence organizational level with a sort of dispersed repeat, the "Alu family". These features suggest that these regions are involved in gene regulation and, also, imply evolutionary events such as duplication or insertion. Comparison of this gene sequence with the rabbit aldolase A complementary DNA sequence revealed some bias in the frequency of nucleotide replacement among the exons, suggesting selective evolutionary conservation of particular exons encoding functional domains. Comparison with the human aldolase B complementary DNA sequence revealed no such tendency; the homology between the two sequences was very high (about 89%), and nucleotide replacements were randomly distributed throughout the protein-coding region.
通过对克隆的基因组DNA进行序列分析，已阐明了编码大鼠醛缩酶同工酶B的染色体基因的结构。该基因由约14×10³个碱基对的DNA组成，被8个间隔序列分隔成9个外显子。通过S1核酸酶保护图谱确定了一个推测的转录起始位点，发现T-A-T-A盒和C-C-A-A-T盒分别位于该起始位点上游25和126个碱基对处。在基因5'端侧翼870个碱基对的区域内有三个100至200个碱基对的特征序列。这些序列两侧均有直接重复序列，并以富含A的核苷酸序列结尾。其中一个与“ID序列”中的一个区域具有模块同源性，据报道该区域是组织特异性基因调控和分化的一个元件。另外两个在序列组织水平上类似于一种分散重复序列“Alu家族”。这些特征表明这些区域参与基因调控，也暗示了诸如复制或插入等进化事件。将该基因序列与兔醛缩酶A互补DNA序列进行比较，发现外显子之间核苷酸替换频率存在一些偏差，这表明编码功能域的特定外显子具有选择性进化保守性。与人类醛缩酶B互补DNA序列进行比较未发现这种趋势；这两个序列之间的同源性非常高（约89%），并且核苷酸替换随机分布在整个蛋白质编码区域。
