Human apolipoprotein E mRNA. cDNA cloning and nucleotide sequencing of a new variant.
Human apolipoprotein E mRNA. cDNA cloning and nucleotide sequencing of a new variant.
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人类载脂蛋白E mRNA。
DOI：
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发表时间：
1984
影响因子：
4.8
通讯作者：
J. Taylor
中科院分区：
文献类型：
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作者：
J. McLean;N. Elshourbagy;D. Chang;R. Mahley;J. Taylor
测定了3个克隆的人肝载脂蛋白E（apo-E）mRNA的cDNA全序列。最长的cDNA序列分析表明，它含有1157个核苷酸的mRNA序列，其中5 '端非翻译区61个核苷酸，信号肽区18个氨基酸，成熟蛋白区299个氨基酸，3'端非翻译区142个核苷酸。从两个cDNA推断的氨基酸序列是相同的，并且对应于先前报道的血浆apo-E3的氨基酸序列（Rall，S. C.的方法，小的，Weisgraber，K. H、和Mahley，R. W.（1982）J.Biol.Chem.257，4171-4178）。第三个cDNA与其他两个cDNA在5个核苷酸位置上不同。这些差异中的三个发生在氨基酸密码子的第三个核苷酸位置，导致在残基瓦尔-85、Ser-223和Gln-248处的相应氨基酸没有变化。另外两个改变的核苷酸发生在密码子的第一个核苷酸位置，导致编码的氨基酸发生变化。在变体序列中，苏氨酸取代残基99处的正常丙氨酸，脯氨酸取代残基152处的正常丙氨酸。我们的结论是，人类肝脏供体是杂合子的基因型。变异的cDNA对应于一种新的，以前未描述的apo-E变异形式，其中蛋白质的氨基酸取代是保守沉默的;它可能无法通过标准的apo-E表型分析方法检测到。152位的氨基酸取代发生在apo-E的区域，该区域似乎对受体结合很重要，并且它可能具有临床意义。
The complete nucleotide sequences of three cloned cDNAs corresponding to human liver apolipoprotein E (apo-E) mRNA were determined. Analysis of the longest cDNA showed that it contained 1157 nucleotides of mRNA sequence with a 5'-terminal nontranslated region of 61 nucleotides, a signal peptide region corresponding to 18 amino acids, a mature protein region corresponding to 299 amino acids, and a 3'-terminal nontranslated region of 142 nucleotides. The inferred amino acid sequences from two cDNAs were identical and corresponded to the amino acid sequence for plasma apo-E3 that has been reported previously ( Rall , S. C., Jr., Weisgraber , K. H., and Mahley , R. W. (1982) J. Biol. Chem. 257, 4171-4178). The third cDNA differed from the other two cDNAs in five nucleotide positions. Three of these differences occurred in the third nucleotide position of amino acid codons, resulting in no change in the corresponding amino acids at residues Val-85, Ser-223, and Gln-248. The other two altered nucleotides occurred in the first nucleotide position of codons, leading to changes in the amino acids encoded. In the variant sequence, a threonine replaced the normal alanine at residue 99 and a proline replaced the normal alanine at residue 152. We have concluded that the human liver donor was heterozygous for the epsilon 3 genotype. The variant cDNA corresponds to a new, previously undescribed variant form of apo-E in which the amino acid substitutions of the protein are electrophoretically silent; it would probably be undetectable by standard apo-E phenotyping methods. The amino acid substitution at position 152 occurs in a region of apo-E that appears to be important for receptor binding, and it may have clinical significance.