A 3,4-dichloroisocoumarin-resistant component of the multicatalytic proteinase complex.
A 3,4-dichloroisocoumarin-resistant component of the multicatalytic proteinase complex.
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多催化蛋白酶复合物的 3,4-二氯异香豆素抗性组分。
DOI：
10.1021/bi00147a023
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发表时间：
1992
期刊：
影响因子：
2.9
通讯作者：
Orlowski,M
中科院分区：
文献类型：
--
作者：
Cardozo,C;Vinitsky,A;Hidalgo,MC;Michaud,C;Orlowski,M
摘要：多催化蛋白酶复合物（MPC）具有三种蛋白水解活性，命名为胰蛋白酶样、胰凝乳蛋白酶样和肽酰谷氨酰肽水解（PGPHA）。基于抑制剂和特异性研究的证据表明，这三种活性中的每一种都与复合物的不同组分有关。丝氨酸蛋白酶抑制剂3，4-二氯异香豆素（DCI）对这三种活性的灭活揭示了额外的DCI抗性组分的存在，其以大于天然未抑制复合物的速率切割天然肽，包括神经降压素、强啡肽、血管紧张素II、胰岛素的氧化B链以及胰岛素原。神经降压素（NT）和胰岛素原降解的反应产物的检查表明，在NT的Ile 12-Leu 13键和牛胰岛素原的连接肽（C-链）内的Leu 44-Ala 45和Val 39-Gly 40键的裂解，表明优先裂解支链氨基酸的羧基侧的键。尽管对DCI的抑制具有抗性，但该组分对异香豆素衍生物7-氨基-4-氯-3-[3-（异硫脲基）丙氧基]异香豆素和4-氯-7-胍基-3-（2-苯乙氧基）异香豆素的抑制敏感。NT的降解被激活亮抑酶肽，凝乳酶抑制剂，和antipain表明，这些醛抑制剂在一个网站的结合可以刺激在不同的网站的复杂的蛋白水解活性。多催化蛋白酶复合物（MPC），又称蛋白酶体，是一种分子量极高的蛋白酶复合物，它的主要组成部分是抗DCI组分（1）~ 700 kDa; 19 S）蛋白酶（21 000-32 000）不相同亚基，代表主要的溶酶体外蛋白水解系统[综述见Orlowski（1990）和Rivett（1989）]。MPC存在于所有真核细胞中，它构成组织匀浆中高达0.5-1.0%的蛋白质，它在进化中高度保守，并且它对于细胞增殖是必需的，这一发现刺激了对MPC日益增长的兴趣（Fujiwara et al.，1991年）。还提出了MPC构成蛋白水解核心的证据（Eytan等人，1989; Drivel和Goldberg，1990）的细胞内蛋白水解的泛素依赖性途径（Hershko，1988; Hough等人，1986，1987，1988; Rechsteiner，1987）。结论MPC可能参与了泛素-
Revised Manuscript Received May 20, 1992 abstract: The multicatalytic proteinase complex (MPC) exhibits three proteolytic activities designated as trypsin-like, chymotrypsin-like, and peptidylglutamyl-peptide hydrolyzing (PGPHA). Evidence based on inhibitor and specificity studies indicates that each of the three activities is associated with a different component of the complex. Inactivation of the three activities by the serine proteinase inhibitor, 3, 4-dichloroisocoumarin (DCI), reveals the presence of an additional DCI-resistant component that cleaves natural peptides including neurotensin, dynorphin, angiotensin II, the oxidized B-chain of insulin, andalso proinsulin at a rate greater than that of the native uninhibited complex. Examination of the reaction products of neurotensin (NT) and proinsulin degradation showed cleavage of the Ile12-Leu13 bond in NT and cleavage of the Leu44-Ala45 and Val39-Gly40 bonds within the connecting peptide (C-chain) of bovine proinsulin, suggesting preferential cleavage of bonds on the carboxyl side of branched chain amino acids. Although resistant to inhibition by DCI, the component was sensitive to inhibition by the isocoumarin derivatives, 7-amino-4-chloro-3-[3-(isothioureido) propoxy] isocoumarin and 4-chloro-7-guanidino-3-(2-phenylethoxy) isocoumarin. Degradation of NT was activated by leupeptin, chymostatin, and antipain indicating that binding of these aldehyde inhibitors at one site can stimulate proteolytic activity at a different site of the complex. The DCI-resistant component seems to constitute a major component of the complex active in degradation of natural peptides and proteins.The multicatalytic proteinase complex (MPC), 1 also re-ferred to as proteasome, isan unusually high molecular mass ('~ 700 kDa; 19S) proteinase composed of multiple low mo-lecular weight (21 000-32 000) nonidentical subunits that represents a major extralysosomal proteolytic system [for reviews, see Orlowski (1990) and Rivett (1989)]. The growing interest in the MPC is stimulated by the finding that it is present in all eukaryotic cells, that it constitutes up to 0.5-1.0% of protein in tissue homogenates, that it is highly conserved in evolution, and that it is essential for cell proliferation (Fujiwara et al., 1991). Evidence was also presented that the MPC constitutes the proteolytic core (Eytan et al., 1989; Driscoll & Goldberg, 1990) of the ubiquitin-dependent pathway of intracellular proteolysis (Hershko, 1988; Hough et al., 1986, 1987, 1988; Rechsteiner, 1987). The conclusion that the MPC might be involved in the ubiquitin-