Identification, purification, and characterization of a PA700-dependent activator of the proteasome
Identification, purification, and characterization of a PA700-dependent activator of the proteasome
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DOI：
10.1074/jbc.271.6.3112
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发表时间：
1996-02-09
影响因子：
4.8
通讯作者：
Slaughter, CA
中科院分区：
文献类型：
--
作者：
DeMartino, GN;Proske, RJ;Slaughter, CA
细胞内蛋白酶（蛋白酶体）的活性由许多特定的调节蛋白调节。其中一个调节因子 PA700 是一种 700,000 Da 多亚基蛋白，它通过一种涉及 ATP 依赖性蛋白酶体-PA700 复合物形成的机制来激活蛋白酶体的水解活性。 PA700 的四个亚基先前已被证明是蛋白质家族的成员，该蛋白质家族包含 ATP 结合的共有序列，并且纯化的 PA700 表达 ATP 酶活性。我们在这里报告了一种新的蛋白酶体调节剂的鉴定、纯化和初步表征。该调节剂对蛋白酶体的活性没有直接影响，但可将蛋白酶体的 PA700 激活增强高达 8 倍。这种激活与含有蛋白酶体/PA700 的复合物的形成有关，该复合物比不存在时形成的复合物要大得多。通过凝胶过滤色谱测定，该调节剂的天然 M(r) 接近 300,000，由三个电泳不同的亚基组成，M(r) 值为 50,000、42,000 和 27,000（分别为 p50、p42 和 p27）。亚基的氨基酸序列分析表明，p50 和 p42 是 PA700 中发现的同一 ATP 结合蛋白家族的成员。 p50 亚基与 TBP1 相同，TBP1 是一种先前报道与人类免疫缺陷病毒 Tat 蛋白相互作用的蛋白质（Nelbock, P., Billion, P. J., Perkins, A., and Rosen, C. A. (1990) Science 248, 1650-1653），而 p42 亚基似乎是该家族的新成员。 p27 亚基与任何先前描述的蛋白质没有显着的序列相似性。 p50 和 p42（但不是 p27）也被鉴定为 PA700 的组成部分，从而使该复合物中 ATP 结合蛋白家族成员的数量增加到 6 个。因此，p50 和 p42 是调节蛋白酶体的两种蛋白质复合物共有的亚基。 PA700 依赖性蛋白酶体激活剂代表了越来越多的调节蛋白酶体活性的蛋白质中的新成员。
The activity of the intracellular protease, the proteasome, is modulated by a number of specific regulatory proteins. One such regulator, PA700, is a 700,000-Da multisubunit protein that activates hydrolytic activities of the proteasome via a mechanism that involves the ATP-dependent formation of a proteasome-PA700 complex. Four subunits of PA700 have been shown previously to be members of a protein family that contains a consensus sequence for ATP binding, and purified PA700 expresses ATPase activity. We report here the identification, purification, and initial characterization of a new modulator of the proteasome. The modulator has no direct effect on the activity of the proteasome, but enhances PA700 activation of the proteasome by up to 8-fold. This activation is associated with the formation of a proteasome/PA700-containing complex that is significantly larger than that formed in its absence. The modulator has a native M(r) of similar to 300,000, as determined by gel filtration chromatography, and is composed of three electrophoretically distinct subunits with M(r) values of 50,000, 42,000, and 27,000 (p50, p42, and p27, respectively). Amino acid sequence analysis of the subunits shows that p50 and p42 are members of the same ATP-binding protein family found in PA700. The p50 subunit is identical to TBP1, a protein previously reported to interact with human immunodeficiency virus Tat protein (Nelbock, P., Billion, P. J., Perkins, A., and Rosen, C. A. (1990) Science 248, 1650-1653), while the p42 subunit seems to be a new member of the family. The p27 subunit has no significant sequence similarity to any previously described protein. Both p50 and p42, but not p27, were also identified as components of PA700, increasing the number of ATP-binding protein family members in this complex to six. Thus, p50 and p42 are subunits common to two protein complexes that regulate the proteasome. The PA700-dependent proteasome activator represents a new member of a growing list of proteins that regulate proteasome activity.