Kobayashi K, Kaneda N, Ichinose H, Kishi F, Nakazawa A, Kurosawa Y, Fujita K, Nagatsu T
Department of Biochemistry, Nagoya University School of Medicine, Aichi.
J Biochem. 1988 Jun;103(6):907-12. doi: 10.1093/oxfordjournals.jbchem.a122386.
Tyrosine hydroxylase (TH) is a rate-limiting enzyme for catecholamine biosynthesis. Recently, Grima et al. (Nature (1987) 326, 707-711) and we (Biochem. Biophys. Res. Commun. (1987) 146, 971-975; Nucleic Acids Res. (1987) 15, 6733) reported four similar but distinct mRNAs that encode human TH. These mRNAs are constant for the major part, but are distinguishable from one another as to the insertion/deletion of 12-bp and 81-bp sequences near the N-terminus. We isolated genomic clones encoding the human TH gene and determined the nucleotide sequence. The human TH gene is split into 14 exons. The 12-bp insertion sequence is encoded by the 3'-terminal portion of the first exon. The 81-bp insertion sequence corresponds to the second exon. Taking into consideration also the results of Southern blot analysis of human genomic DNA, we concluded that the four types of human TH mRNA are produced through alternative splicing from a single gene. Two kinds of alternative splicing are involved: the alternative use of two donor sites in the first exon, and the inclusion/exclusion of the second exon. We propose a possible secondary structure for the latter alternative splicing pathway.
酪氨酸羟化酶（TH）是儿茶酚胺生物合成的限速酶。最近，格里马等人（《自然》（1987年）326卷，707 - 711页）以及我们（《生物化学与生物物理研究通讯》（1987年）146卷，971 - 975页；《核酸研究》（1987年）15卷，6733页）报道了四种相似但不同的编码人TH的mRNA。这些mRNA在大部分区域是恒定的，但在N端附近12bp和81bp序列的插入/缺失方面彼此可区分。我们分离了编码人TH基因的基因组克隆并确定了核苷酸序列。人TH基因被分成14个外显子。12bp的插入序列由第一个外显子的3'末端部分编码。81bp的插入序列对应于第二个外显子。考虑到人基因组DNA的Southern印迹分析结果，我们得出结论，四种类型的人TH mRNA是通过一个单一基因的可变剪接产生的。涉及两种可变剪接：第一个外显子中两个供体位点的交替使用，以及第二个外显子的包含/排除。我们为后一种可变剪接途径提出了一种可能的二级结构。
