Distinct C-terminal sequences of isozymes I and II of the human erythrocyte L-isoaspartyl/D-aspartyl protein methyltransferase.
Distinct C-terminal sequences of isozymes I and II of the human erythrocyte L-isoaspartyl/D-aspartyl protein methyltransferase.
复制标题
人红细胞 L-异天冬氨酰/D-天冬氨酰蛋白甲基转移酶同工酶 I 和 II 的不同 C 端序列。
DOI：
10.1016/s0006-291x(05)81242-2
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发表时间：
1991
影响因子：
3.1
通讯作者：
Clarke,S
中科院分区：
文献类型：
--
作者：
Ingrosso,D;Kagan,RM;Clarke,S
我们纯化了人红细胞L-异戊酰/D-戊酰甲基转移酶的酸性更强的主要同工酶（II），并将其结构与先前测序的同工酶I进行了比较。这些同工酶都是25，000分子量多肽的单体，具有相似的酶性质，但等电点相差一个pH单位。对占同工酶I序列89%的同工酶II的16个胰蛋白酶肽段的分析表明，这些酶形式之间没有差异。然而，对葡萄球菌V8蛋白酶C-末端片段的分析显示，这些蛋白质的最后两个残基不同。同工酶I的-Trp-Lys-COOH末端在同工酶II中被Asp-Asp-COOH末端取代。基因组DNA的Southern印迹分析表明，人类染色体可能只含有编码该酶的单个基因。我们建议，不同的C-末端的同工酶I和II可以产生从多个mRNA的选择性剪接的产生。
We have purified the more acidic major isozyme (II) of the human erythrocyte L-isoaspartyl/D-aspartyl methyltransferase and compared its structure to that of the previously sequenced isozyme I. These isozymes are both monomers of 25,000 molecular weight polypeptides and have similar enzymatic properties, but have isoelectric points that differ by one pH unit. Analysis of 16 tryptic peptides of isozyme II accounting for 89% of the sequence of isozyme I revealed no differences between these enzyme forms. However, analysis of aStaphylococcalV8 protease C-terminal fragment revealed that the last two residues of these proteins differed. The -Trp-Lys-COOH terminus of isozyme I is replaced by a Asp-Asp-COOH terminus in isozyme II. Southern blot analysis of genomic DNA suggests that the human chromosome may contain only a single gene encoding the enzyme. We propose that the distinct C-termini of isozymes I and II can arise from the generation of multiple mRNA's by alternative splicing.