Maeda H, Hashimoto R K, Ogura T, Hiraga S, Uzawa H
Department of Molecular Genetics, Kumamoto University Medical School, Japan.
J Lipid Res. 1987 Dec;28(12):1405-9.
Apolipoprotein C-III (apoC-III) is a major protein of very low density lipoprotein (VLDL). The apoC-III polypeptide contains a carbohydrate chain containing galactosamine, galactose, and sialic acid attached in O-linkage to a threonine residue at position 74. We have cloned the apoC-III gene from a subject whose serum contained unusually high amounts of apoC-III lacking the carbohydrate moiety (C-III-0). DNA sequence analysis of the cloned gene revealed a single nucleotide substitution (A----G) that encodes an alanine at position 74 instead of the normal threonine. As a result of this amino acid replacement, the mutant apoC-III polypeptide is not glycosylated. The mutation in the apoC-III gene creates a novel AluI site that permits diagnosis of the change by Southern blotting of genomic DNA.
载脂蛋白C-III（apoC-III）是极低密度脂蛋白（VLDL）的主要蛋白质。apoC-III多肽含有一条碳水化合物链，该链包含以O-连接方式连接到第74位苏氨酸残基上的半乳糖胺、半乳糖和唾液酸。我们从一名血清中含有异常高含量缺乏碳水化合物部分的apoC-III（C-III-0）的受试者中克隆了apoC-III基因。对克隆基因的DNA序列分析显示，存在一个单核苷酸替换（A→G），该替换在第74位编码丙氨酸而非正常的苏氨酸。由于这种氨基酸替换，突变的apoC-III多肽未被糖基化。apoC-III基因中的突变产生了一个新的AluI位点，这使得通过基因组DNA的Southern印迹法能够诊断出这种变化。
