Backus J W, Eagleton M J, Harris S G, Sparks C E, Sparks J D, Smith H C
Department of Biochemistry, University of Rochester, NY 14642.
Biochem Biophys Res Commun. 1990 Jul 31;170(2):513-8. doi: 10.1016/0006-291x(90)92121-f.
The mRNA for apolipoprotein B is translated into either a high molecular weight (apo BH) or low molecular weight (apo BL) form of the protein depending on a novel form of RNA processing known as RNA editing. Apo BH mRNA editing is both tissue-specific and hormonally regulated and involves transition of cytidine to uridine at codon 2153 thereby converting a glutamine codon (CAA) to a translational stop codon (UAA). Three methods for quantitating the endogenous levels of liver apo B mRNA editing were compared: (1) Southern blot hybridization with discriminative thermal washes, (2) competimer-hybridization with discriminative thermal washes and (3) competimer-polymerase chain reaction (competimer-PCR). The data suggest that hybridization and PCR can yield similar quantitation when competing oligonucleotides are used. Based on competimer-PCR it is proposed that 40% and 85% of normal rat liver and small intestine apo B mRNA (respectively) are edited.
载脂蛋白B的信使核糖核酸（mRNA）根据一种名为RNA编辑的新型RNA加工形式，被翻译成高分子量（apo BH）或低分子量（apo BL）形式的蛋白质。Apo BH mRNA编辑具有组织特异性且受激素调节，涉及密码子2153处胞苷向尿苷的转变，从而将谷氨酰胺密码子（CAA）转换为翻译终止密码子（UAA）。比较了三种定量肝脏apo B mRNA编辑内源性水平的方法：（1）采用鉴别性热洗脱的Southern印迹杂交法，（2）采用鉴别性热洗脱的竞争物杂交法，以及（3）竞争物聚合酶链反应（竞争物-PCR）。数据表明，当使用竞争性寡核苷酸时，杂交法和PCR法可产生相似的定量结果。基于竞争物-PCR法，提出正常大鼠肝脏和小肠apo B mRNA分别有40%和85%被编辑。
