Molecular cloning and nucleotide sequence of cDNA encoding the rat kidney S-adenosylmethionine synthetase.
Molecular cloning and nucleotide sequence of cDNA encoding the rat kidney S-adenosylmethionine synthetase.
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DOI：
10.1016/s0021-9258(18)77403-6
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发表时间：
1990-08
期刊：
影响因子：
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通讯作者：
S. Horikawa;J. Sasuga;K. Shimizu;Hisashi OzasaS;K. Tsukada
中科院分区：
文献类型：
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作者：
S. Horikawa;J. Sasuga;K. Shimizu;Hisashi OzasaS;K. Tsukada
我们以前报道的分离的cDNA编码的肝脏特异性同工酶的大鼠S-腺苷甲硫氨酸合成酶从λ gt 11大鼠肝脏cDNA文库。使用此cDNA作为探针，我们已经分离和测序的cDNA克隆大鼠肾S-腺苷甲硫氨酸合成酶（肝外同工酶）从λ gt 11大鼠肾cDNA文库。从两个重叠的cDNA克隆获得该酶mRNA的完整编码序列。氨基酸序列分析表明，该酶由395个氨基酸组成，分子量为43，715 Da，与大鼠肝S-腺苷甲硫氨酸合成酶的氨基酸序列有85%的相似性。这一结果表明，肾脏和肝脏同工酶可能起源于一个共同的祖先基因。此外，不同物种之间已知的S-腺苷甲硫氨酸合成酶序列的比较也表明，这些蛋白质具有高度的相似性。肾脏和肝脏型S-腺苷甲硫氨酸合成酶mRNA在肾脏，肝脏，大脑和睾丸中的分布进行了检查，通过RNA印迹杂交分析与探针特异性各自的mRNA。一个3.4 kb的mRNA物种与肾脏S-腺苷甲硫氨酸合成酶的探针杂交被发现在所有组织检查，除了肝脏，而3.4 kb的mRNA物种与肝脏S-腺苷甲硫氨酸合成酶的探针杂交只存在于肝脏。3.4 kb的肾型同工酶mRNA显示相同的分子大小的肝型同工酶mRNA。因此，肾脏和肝脏型S-腺苷甲硫氨酸合成酶同工酶mRNA在不同组织中表达，具有不同的组织特异性。
We previously reported the isolation of a cDNA encoding the liver-specific isozyme of rat S-adenosylmethionine synthetase from a lambda gt11 rat liver cDNA library. Using this cDNA as a probe, we have isolated and sequenced cDNA clones for the rat kidney S-adenosylmethionine synthetase (extrahepatic isoenzyme) from a lambda gt11 rat kidney cDNA library. The complete coding sequence of this enzyme mRNA was obtained from two overlapping cDNA clones. The amino acid sequence deduced from the cDNAs indicates that this enzyme contains 395 amino acids and has a molecular mass of 43,715 Da. The predicted amino acid sequence of this protein shares 85% similarity with that of rat liver S-adenosylmethionine synthetase. This result suggests that kidney and liver isoenzymes may have originated from a common ancestral gene. In addition, comparison of known S-adenosylmethionine synthetase sequences among different species also shows that these proteins have a high degree of similarity. The distribution of kidney- and liver-type S-adenosylmethionine synthetase mRNAs in kidney, liver, brain, and testis were examined by RNA blot hybridization analysis with probes specific for the respective mRNAs. A 3.4-kilobase (kb) mRNA species hybridizable with a probe for kidney S-adenosylmethionine synthetase was found in all tissues examined except for liver, while a 3.4-kb mRNA species hybridizable with a probe for liver S-adenosylmethionine synthetase was only present in the liver. The 3.4-kb kidney-type isozyme mRNA showed the same molecular size as the liver-type isozyme mRNA. Thus, kidney- and liver-type S-adenosylmethionine synthetase isozyme mRNAs were expressed in various tissues with different tissue specificities.