Jardi R, Rodriguez F, Miravitlles M, Vidal R, Cotrina M, Quer J, Pascual C, Weidinger S
Department of Biochemistry, Hospital Universitario Valle Hebrón. Barcelona, Spain. Rjardi ar.vhebron.es
Hum Mutat. 1998;12(3):213.
To characterize the molecular basis of the "new" alpha1-antitrypsin (alpha1AT) deficient variant, PI Y barcelona, DNA sequence analysis of the coding exons of the alpha1AT gene was carried out using an amplification DNA technique and direct sequencing. The PI Y barcelona allele differs from the normal M1(Val213) allele sequence by two point substitutions: a transversion of GAT TO GTT in exon III in the codon for residue 256, resulting in the amino acid change of Asp256 to Val256, and a transversion of CCC to CAC in exon V in the codon for residue 391, resulting in the amino acid substitution of Pro391 to His391. On isoelectric focusing analysis these substitutions result in a cathodal migration of the "new" variant close to the PI Z. The index case, diagnosed with severe obstructive pulmonary disease, initially phenotyped a PI ZZ, was homozygous for PI Y barcelona. The patient's serum alpha1AT level was 16 mg/dL (normal values 115-220 mg/dL). Inheritance of the PI Y barcelona was confirmed by family study. Amino acid substitution in postion 391 occurs in the C-terminal peptide region, which shows a high degree of homology with the family of serpins. Pro391 is considered to have special relevance in the secretion of alpha1AT.
为了表征“新型”α1-抗胰蛋白酶（α1AT）缺陷变体PI巴塞罗那的分子基础，采用扩增DNA技术和直接测序法对α1AT基因的编码外显子进行了DNA序列分析。PI巴塞罗那等位基因与正常的M1（Val213）等位基因序列有两个点突变：外显子III中第256位密码子的GAT突变为GTT，导致氨基酸Asp256变为Val256；外显子V中第391位密码子的CCC突变为CAC，导致氨基酸Pro391替换为His391。在等电聚焦分析中，这些突变导致“新型”变体向阴极迁移，接近PI Z。首例被诊断为重度阻塞性肺疾病的患者最初表现为PI ZZ表型，其PI巴塞罗那为纯合子。患者血清α1AT水平为16mg/dL（正常值为115 - 220mg/dL）。通过家系研究证实了PI巴塞罗那的遗传。391位的氨基酸替换发生在C末端肽区域，该区域与丝氨酸蛋白酶抑制剂家族具有高度同源性。Pro391被认为在α1AT的分泌中具有特殊意义。
