Land S J, Jones R F, King C M
Department of Chemical Carcinogenesis, Michigan Cancer Foundation, Detroit 48201.
Carcinogenesis. 1994 Aug;15(8):1585-95. doi: 10.1093/carcin/15.8.1585.
Cytosolic activities in liver, stomach, small intestine, colon, lung, kidney, brain and spleen of hamster have been shown to be capable of N-acetylation, O-acetylation and N,O-acetyltransfer utilizing aromatic amine derivatives as substrates. These activities, which have been implicated in the metabolic activation and carcinogenicity of these compounds, were highest in the liver and small intestine. N-Acetylation could be demonstrated with either acetyl CoA or N-hydroxy-N-acetylaminoarenes serving as acetyl donors. Each of these tissues gave two immunoreactive bands (approximately 29 and 31 kDa) on Western blots using anti-rat AT monoclonal antibodies for detection. Single copies of two distinct acetyltransferase genes, designated AT1 and AT2, were detected in hamster DNA by Southern blot analysis using gene-specific hybridization probes for the 3' end of the AT coding regions. A third gene with > 80% sequence similarity to codons 118-158 of AT2 was also detected. Sequence analysis of the two AT genes showed that both had intronless, 0.87 kb coding regions. One was identical with the AT1 reported by Abu-Zeid et al. (Abu-Zeid,M., Nagata, K., Miyata,M., Ozawa,S., Fukuhara,M. and Yamazoe,Y., 1991, An arylamine acetyltransferase (AT-1) from Syrian golden hamster liver: cloning, complete nucleotide sequence, and expression in mammalian cells. Mol. Carcinogen., 4, 81-88). The second, AT2 (GenBank accession number L24912), coded for a 290 amino acid sequence that was 79% homologous with hamster AT1 and had a calculated molecular weight of 33.8 kDa, a theoretical pI of 5.96 and the three cysteines that have been conserved in all known vertebrate ATs at positions 44, 68 and 223. Northern blot hybridization using gene-specific AT probes detected mRNAs for both AT1 and AT2 in each of the eight tissues analyzed. Two AT1 transcripts, approximately 1.7 and 2.3 kb, were found in approximately equal ratios in all eight tissues. Three transcripts for AT2, approximately 1.9, 2.1 and 2.4 kb, were present in approximately equal ratios in the brain, small intestine, lung and colon. The liver, stomach, kidney and spleen had primarily the smaller two AT2 mRNAs. The overall abundance of AT mRNAs was highest in liver, small intestine and colon. The coding sequences of all AT mRNAs analyzed were identical to their corresponding genes, although the lengths of both the 5' and 3' untranslated transcript regions varied.(ABSTRACT TRUNCATED AT 400 WORDS)
仓鼠肝脏、胃、小肠、结肠、肺、肾、脑和脾脏中的胞质活性已被证明能够利用芳香胺衍生物作为底物进行N - 乙酰化、O - 乙酰化和N,O - 乙酰转移。这些活性与这些化合物的代谢活化和致癌性有关，在肝脏和小肠中最高。以乙酰辅酶A或N - 羟基 - N - 乙酰氨基芳烃作为乙酰供体时均可证明N - 乙酰化。使用抗大鼠AT单克隆抗体进行检测时，这些组织中的每一个在蛋白质免疫印迹上都出现两条免疫反应带（约29 kDa和31 kDa）。通过使用针对AT编码区3'端的基因特异性杂交探针进行Southern印迹分析，在仓鼠DNA中检测到两个不同的乙酰转移酶基因的单拷贝，分别命名为AT1和AT2。还检测到第三个基因，其与AT2的第118 - 158密码子的序列相似性> 80%。对这两个AT基因的序列分析表明，它们都有0.87 kb的无内含子编码区。其中一个与Abu - Zeid等人报道的AT1相同（Abu - Zeid,M., Nagata, K., Miyata,M., Ozawa,S., Fukuhara,M.和Yamazoe,Y., 1991, 来自叙利亚金黄仓鼠肝脏的芳胺乙酰转移酶(AT - 1): 克隆、完整核苷酸序列及在哺乳动物细胞中的表达。Mol. Carcinogen., 4, 81 - 88）。第二个基因AT2（GenBank登录号L24912）编码一个290个氨基酸的序列，与仓鼠AT1的同源性为79%，计算分子量为33.8 kDa，理论pI为5.96，并且在所有已知脊椎动物AT的第44、68和223位都有保守的三个半胱氨酸。使用基因特异性AT探针进行Northern印迹杂交，在分析的八个组织中的每一个中都检测到了AT1和AT2的mRNA。在所有八个组织中发现了两种AT1转录本，约1.7 kb和2.3 kb，比例大致相等。AT2有三种转录本，约1.9、2.1和2.4 kb，在脑、小肠、肺和结肠中的比例大致相等。肝脏、胃、肾和脾脏主要含有较小的两种AT2 mRNA。AT mRNA的总体丰度在肝脏、小肠和结肠中最高。分析的所有AT mRNA的编码序列与其相应基因相同，尽管5'和3'非翻译转录区的长度有所不同。（摘要截断于400字）
