Joh T H, Baetge E E, Reis D J
Hypertension. 1984 Sep-Oct;6(5 Pt 2):II1-6. doi: 10.1161/01.hyp.6.5_pt_2.ii1.
We have postulated that the catecholamine-synthesizing enzymes tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and phenylethanolamine N-methyltransferase (PNMT) are coded for by similar genes. To analyze the structural relationship of genes coding for these enzymes, we have cloned DNAs complementary (cDNA) to DBH and PNMT messenger RNAs (mRNAs). Using hybrid selection analysis to identify the cDNA clones positively, we discovered cross-hybridization between DBH cDNA clones and PNMT mRNA and between PNMT cDNA clones and DBH mRNA. Further analysis by RNA blot hybridization revealed that the DBH cDNA probe hybridized predominantly to a 5500 nucleotide mRNA and less strongly to a 1100 nucleotide species, and the PNMT cDNA probe hybridized strongly to the 1100 nucleotide mRNA and weakly to the 5500 nucleotide message. DNA blot hybridization analysis demonstrated that DBH and PNMT cDNA probes hybridized to several common restriction fragments of total cellular DNA. The evidence presented here suggests the existence of homologous gene-coding regions in DBH and PNMT cDNAs. These homologies may be the result of duplication of a common ancestral gene. DNA blot analysis suggests that these enzymes are coded for by single genes, which may be located in close proximity to each other in the DNA, and points to the existence of either a single gene or linked genes coding for all catecholamine enzymes.
我们推测，儿茶酚胺合成酶酪氨酸羟化酶（TH）、多巴胺β-羟化酶（DBH）和苯乙醇胺N-甲基转移酶（PNMT）由相似的基因编码。为了分析编码这些酶的基因的结构关系，我们克隆了与DBH和PNMT信使核糖核酸（mRNA）互补的DNA（cDNA）。通过杂交选择分析来阳性鉴定cDNA克隆，我们发现DBH cDNA克隆与PNMT mRNA之间以及PNMT cDNA克隆与DBH mRNA之间存在交叉杂交。通过RNA印迹杂交进一步分析表明，DBH cDNA探针主要与一种5500个核苷酸的mRNA杂交，与一种1100个核苷酸的mRNA杂交较弱；而PNMT cDNA探针与1100个核苷酸的mRNA杂交强烈，与5500个核苷酸的mRNA杂交较弱。DNA印迹杂交分析表明，DBH和PNMT cDNA探针与总细胞DNA的几个共同限制性片段杂交。此处提供的证据表明DBH和PNMT cDNA中存在同源基因编码区。这些同源性可能是一个共同祖先基因重复的结果。DNA印迹分析表明，这些酶由单个基因编码，这些基因在DNA中可能彼此紧邻，并表明存在一个编码所有儿茶酚胺酶的单个基因或连锁基因。
