Tsuji H
Second Department of Medicine, Kyoto Prefectural University of Medicine.
Rinsho Ketsueki. 1991 May;32(5):481-6.
Antithrombin III (AT III) has been confirmed to play an important role as a serine protease inhibitor in the mechanism of blood coagulation, and its deficiency or abnormality is found to cause thromboembolic disorders by reducing the anticoagulant activity. In this paper AT III gene of patient with congenital AT III deficiency, which was suggested to have qualitative abnormality by isoelectric focusing, was investigated. Analysis of the genomic structure by Southern blot hybridization with a cDNA probe (pAT6) revealed no detectable changes indicating any deletions, rearrangements and translocations. Therefore, we focused to analyze the sequence of exon 6 of AT III gene by polymerase chain reaction (PCR) methods followed by direct sequencing analysis. Nucleotide sequencing of exon 6 of AT III gene showed a G to T transitional mutation resulting in the conversion of arginine-406 to methionine coexisted with normal allele which encodes arginine. The mutation is located near the reactive center of AT III molecule, which region has been proved to be highly conserved during the evolution of serine protease inhibitor (serpin) family. From these results, it is concluded that the new type of mutation at amino acid site 407, which is similar to AT III Utah, is important for maintaining the structural and biological function of this inhibitor.
抗凝血酶III（AT III）已被证实在血液凝固机制中作为丝氨酸蛋白酶抑制剂发挥重要作用，并且发现其缺乏或异常会通过降低抗凝活性导致血栓栓塞性疾病。本文对一名先天性AT III缺乏患者的AT III基因进行了研究，该患者经等电聚焦提示存在定性异常。用cDNA探针（pAT6）进行Southern印迹杂交分析基因组结构，未发现表明任何缺失、重排和易位的可检测变化。因此，我们集中精力通过聚合酶链反应（PCR）方法分析AT III基因外显子6的序列，随后进行直接测序分析。AT III基因外显子6的核苷酸测序显示存在一个从G到T的转换突变，导致精氨酸-406转变为甲硫氨酸，且与编码精氨酸的正常等位基因共存。该突变位于AT III分子的反应中心附近，该区域在丝氨酸蛋白酶抑制剂（serpin）家族的进化过程中已被证明高度保守。从这些结果可以得出结论，类似于AT III Utah的氨基酸位点407处的新型突变对于维持该抑制剂的结构和生物学功能很重要。
