Identification and functional analysis of human Tom22 for protein import into mitochondria
Identification and functional analysis of human Tom22 for protein import into mitochondria
复制标题
DOI：
10.1128/mcb.20.19.7205-7213.2000
复制
发表时间：
2000-10-01
影响因子：
5.3
通讯作者：
Mori, M
中科院分区：
文献类型：
--
作者：
Yano, M;Hoogenraad, N;Mori, M
线粒体在外膜上有一个受体复合物，它识别并转运在胞质溶胶中合成的线粒体蛋白。本文报道了人Tom 22（hTom 22）的鉴定和功能分析。hTom 22具有暴露于胞质溶胶的N-末端带负电荷的区域、推定的跨膜区域和具有很少负电荷的C-末端膜间空间区域。Tom 22与Tom 20形成复合物，并且其胞质结构域作为真菌中的输入受体起作用。使用前鸟氨酸转氨甲酰酶（pOTC）衍生物和一系列hTom 22缺失突变体的输入抑制测定表明，胞质结构域的C-末端区段对于前序列结合是重要的，而N-末端结构域对于pOTC的成熟部分的结合是重要的。没有获得pOTC与Tom 22膜间空间结构域相互作用的证据。结合研究显示，前序列对于pOTC与Tom 20的结合至关重要，而前序列和成熟部分对于与Tom 22的结合都很重要。无细胞免疫沉淀试验表明，Tom 22胞质结构域的内部区段对于与Tom 20的相互作用是重要的。
Mitochondria have a receptor complex in the outer membrane which recognizes and translocates mitochondrial proteins synthesized in the cytosol. We report here the identification and functional analysis of human Tom22 (hTom22). hTom22 has an N-terminal negatively charged region exposed to the cytosol, a putative transmembrane region, and a C-terminal intermembrane space region with little negative charge. Tom22 forms a complex with Tom20, and its cytosolic domain functions as an import receptor as in fungi. An import inhibition assay, using pre-ornithine transcarbamylase (pOTC) derivatives and a series of hTom22 deletion mutants, showed that the C-terminal segment of the cytosolic domain is important for presequence binding, whereas the N-terminal domain is important for binding to the mature portion of pOTC. No evidence for pOTC interaction with the Tom22 intermembrane space domain was obtained. Binding studies revealed that the presequence is critical for pOTC binding to Tom20, whereas both the presequence and mature portion are important for binding to Tom22. A cell-free immunoprecipitation assay indicated that an internal segment of the Tom22 cytosolic domain is important for interaction with Tom20.