Nakayama M, Nagata K, Kato A, Ishihama A
Department of Molecular Genetics, National Institute of Genetics, Shizuoka, Japan.
J Biol Chem. 1991 Nov 15;266(32):21404-8.
The murine Mx1 protein is an interferon-inducible nuclear protein and confers resistance to influenza virus infection even though the resistance mechanism is yet unclear. The Mx1 protein contains a tripartite GTP-binding domain consisting of GXXXXGKS, DXXG, and T/NKXD motifs. In the GTPase gene superfamily such as p21ras protein, signal-transducing G protein, and translation elongation factor, the GTPase activity plays a key role in each protein function. Here we show that GTPase activity is indeed associated with the intact Mx1 protein purified from Escherichia coli expressing Mx1 cDNA. Amino acid substitution within the GTP-binding motif led to significant reduction in the GTPase activity. Yeast vacuolar protein sorting (VPS1) protein and the rat microtubule-associated mechanochemical enzyme dynamin were found to be homologous to Mx1 not only in the tripartite GTP-binding motif, but also in the amino-terminal region of approximately 300 amino acids in length. The function of Mx1 is discussed in comparison with these proteins.
小鼠Mx1蛋白是一种干扰素诱导的核蛋白，尽管其抗性机制尚不清楚，但它能赋予对流感病毒感染的抗性。Mx1蛋白包含一个由GXXXXGKS、DXXG和T/NKXD基序组成的三联体GTP结合结构域。在诸如p21ras蛋白、信号转导G蛋白和翻译延伸因子等GTP酶基因超家族中，GTP酶活性在每种蛋白质功能中都起着关键作用。在这里，我们表明GTP酶活性确实与从表达Mx1 cDNA的大肠杆菌中纯化的完整Mx1蛋白相关。GTP结合基序内的氨基酸取代导致GTP酶活性显著降低。发现酵母液泡蛋白分选（VPS1）蛋白和大鼠微管相关机械化学酶发动蛋白不仅在三联体GTP结合基序上，而且在长度约为300个氨基酸的氨基末端区域与Mx1同源。我们将Mx1的功能与这些蛋白质进行了比较讨论。
