Molecular identification of adrenal inner zone antigen as a heme-binding protein
Molecular identification of adrenal inner zone antigen as a heme-binding protein
复制标题
DOI：
10.1111/j.1742-4658.2005.04977.x
复制
发表时间：
2005-11-01
期刊：
影响因子：
5.4
通讯作者：
Okamoto, M
中科院分区：
文献类型：
--
作者：
Min, L;Strushkevich, NV;Okamoto, M
肾上腺内区抗原（IZA），它与单克隆抗体特异性反应，对大鼠肾上腺的束状带和网状带，以前被发现是相同的蛋白质不同命名为25-Dx和膜相关的孕酮受体。IZA被纯化为谷胱甘肽S-转移酶融合蛋白或His（6）融合蛋白，并对其分子特性进行了研究。纯化蛋白的紫外-可见吸收光谱和电子顺磁共振谱表明，IZA结合的是高自旋型的血红素发色团。血红素分析表明它是B型。进行定点诱变研究以鉴定将血红素结合至蛋白质的氨基酸残基。结果表明，两个Tyr残基，Tyr 107和Tyr 113，和一个肽段，D99-K102，是重要的锚定血红素进入疏水口袋。在COS-7细胞表达系统中研究了IZA对类固醇21-羟基化反应的影响。结果表明，IZA与CYP 21的共存增强了21-羟化酶活性。
The adrenal inner zone antigen (IZA), which reacts specifically with a monoclonal antibody raised against the fasciculata and reticularis zones of the rat adrenal, was previously found to be identical with a protein variously named 25-Dx and membrane-associated progesterone receptor. IZA was purified as a glutathione S-transferase-fused or His(6)-fused protein, and its molecular properties were studied. The UV-visible absorption and EPR spectra of the purified protein showed that IZA bound a heme chromophore in high-spin type. Analysis of the heme indicated that it is of the b type. Site-directed mutagenesis studies were performed to identify the amino-acid residues that bind the heme to the protein. The results suggest that two Tyr residues, Tyr107 and Tyr113, and a peptide stretch, D99-K102, were important for anchoring the heme into a hydrophobic pocket. The effect of IZA on the steroid 21-hydroxylation reaction was investigated in COS-7 cell expression systems. The results suggest that the coexistence of IZA with CYP21 enhances 21-hydroxylase activity.