Aburatani H, Matsumoto A, Ishikawa T, Takaku F, Itakura H
Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo.
J Biochem. 1989 Jun;105(6):911-5. doi: 10.1093/oxfordjournals.jbchem.a122778.
The molecular mechanism of human intestinal apolipoprotein (apo) B-48 synthesis has been elucidated by a combination of sequencing of cloned complementary DNAs and RNase cleavage analysis of RNA heteroduplex. All intestinal cDNA clones contained a single C to T base substitution in the codon CAA encoding Gln2153 in apoB-100 cDNA, resulting in a translational stop. One of the our intestinal apoB cDNA clones was polyadenylated 106 bases downstream from the stop codon, possibly producing a 7-kb apoB message in the intestine. RNase cleavage analysis of the RNA heteroduplex between hepatic or intestinal RNA and apoB cDNA-directed anti-sense RNA showed that this single C to U substitution may occur in most of intestinal apoB mRNA. These results suggested that human apoB-48 is mostly produced by apoB mRNA with an in-frame stop codon in the intestine.
通过克隆互补DNA测序与RNA异源双链体的核糖核酸酶切割分析相结合，已阐明了人类肠道载脂蛋白（apo）B-48合成的分子机制。所有肠道cDNA克隆在apoB-100 cDNA中编码Gln2153的密码子CAA处都有一个从C到T的单碱基替换，导致翻译终止。我们的一个肠道apoB cDNA克隆在终止密码子下游106个碱基处进行了多聚腺苷酸化，可能在肠道中产生一个7kb的apoB信使RNA。肝或肠道RNA与apoB cDNA导向的反义RNA之间的RNA异源双链体的核糖核酸酶切割分析表明，这种从C到U的单碱基替换可能发生在大多数肠道apoB mRNA中。这些结果表明，人类apoB-48主要由肠道中具有框内终止密码子的apoB mRNA产生。
