Chen K, Wu H F, Shih J C
Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles 90033.
J Neurochem. 1993 Jul;61(1):187-90. doi: 10.1111/j.1471-4159.1993.tb03554.x.
Monoamine oxidases (MAOs) A and B play important roles in the metabolism of neuroactive, vasoactive amines. Human platelets contain only MAO B, often used as an indicator of brain MAO B. The validity of this model remained to be evaluated. This report describes the molecular cloning of human MAO B from frontal cortex and platelets. Two overlapping PCR-amplified clones of human platelet MAO B and four PCR-amplified clones of human frontal cortex MAO B covering the entire coding region were sequenced using five internal oligomers and M13 reverse and forward primers. The nucleotide sequences of human MAO B cDNA from platelet and frontal cortex were identical to that of human liver MAO B except for three nucleotides that differed in frontal cortex: nucleotides 440 A-->G, 794 C-->T, and 825 C-->T. Whether or not these differences are artifactual, all three represent silent mutations, which would not alter the amino acid of the encoded polypeptides. Thus, the deduced amino acid sequences of MAO B from frontal cortex, platelet, and liver are identical. These findings indicate the validity of using platelet MAO B mRNA as a marker for brain MAO B and provide a new approach to study the role of brain MAO B in humans.
单胺氧化酶（MAO）A和B在神经活性、血管活性胺类的代谢中起重要作用。人类血小板仅含有MAO B，常被用作脑MAO B的指标。该模型的有效性仍有待评估。本报告描述了从额叶皮质和血小板中克隆人MAO B的分子过程。使用五个内部寡核苷酸以及M13正向和反向引物，对覆盖整个编码区的两个重叠的人血小板MAO B的PCR扩增克隆和四个人额叶皮质MAO B的PCR扩增克隆进行了测序。除了额叶皮质中三个不同的核苷酸外，来自血小板和额叶皮质的人MAO B cDNA的核苷酸序列与人类肝脏MAO B的核苷酸序列相同：核苷酸440处A→G、794处C→T和825处C→T。无论这些差异是否为假象，这三处均代表沉默突变，不会改变所编码多肽的氨基酸。因此，从额叶皮质、血小板和肝脏中推导的MAO B氨基酸序列是相同的。这些发现表明使用血小板MAO B mRNA作为脑MAO B标志物的有效性，并为研究脑MAO B在人类中的作用提供了新方法。
