PSMB7 (E1L5H) Rabbit mAb

• 产品编号：CST-13207S      品牌：CST       原厂货号：13207S
• 产品分类：抗体 > 一抗 > 蛋白特异性一抗
• 应用分类：

描述：

PSMB7 (E1L5H) Rabbit mAb兔单抗识别内源性的总PSMB7蛋白。此抗体与PSMB7的前体和成熟蛋白反应。但与PSMB10无交叉反应性。此抗体经合成与人源PSMB7蛋白的Lys237邻近氨基酸残基序列一致的肽段，免疫动物产生。26S蛋白酶体是一种高丰度，大小约2 MDa的复合物，它具有泛素蛋白酶体途径的蛋白水解臂。它主要由两种亚型复合物组成，19S调节颗粒(RP)和20S催化核心颗粒(CP)，在许多情况下RPs会覆盖CP的任一末端。CP由包含催化位点的2种堆积β-环组成，每一种β-环由7种亚基组成(β_1-7)，且两侧包含两个分别由七个亚基构成的α环 (α_1-7).。因此，20S CP 的结构为α_1-7β_1-7β_1-7α_1-7。RP包括了一个底部和一个盖子。部分底部由ATPases的六角环组成，功能为打开底物蛋白和打开α-亚基交错的N-末端片段的闸门，从而使得未折叠的底物进入催化部位。盖子主要起特异性识别泛素信号的作用(1)。除了19S帽子之外，其他的蛋白和复合物，例如蛋白酶体活化因子28 (PA28/11S)，与20S的筒状末端结合，从而促进闸门的开放和激活。此外，蛋白酶体相关的DUBs和E3s能够改变底物嵌合的多泛素链，这可能调节了它们对降解的敏感性(2)。核心颗粒由它内部的三种催化活性类型构成：糜蛋白酶样、胰蛋白酶样和半胱天冬酶样活性，由组成性表达的PSMB5 (β5/MB1/X/LMPX/Macropain epsilon链), PSMB7 (β2/Z/Macropain 链 Z)和PSMB6 (β1/Y/LMPY/Macropain delta 链)亚基分别组成。这些催化亚基属于N-末端亲核(Ntn)水解酶家族，并有标志性的单一残基活化位点。每一种蛋白水解亚基的N-末端苏氨酸提供催化的亲核体（在侧链上）和主要的质子接受体（在主要的链N-末端）。β-催化亚基由N-末端前肽合成，通过限制性蛋白水解暴露于催化的苏氨酸残基，在蛋白酶体发生的最后被去除(3)。免疫应答的免疫细胞中，组成性地表达PSMB6、PSMB、PSMB5亚基被3种高度同源的诱导β-亚基：PSMB9 (β1i/LMP2/RING12), PSMB10 (β2i/MECL-1/LMP10) 和 PSMB8 (β5i/LMP7/RING10)分别替代，从而形成免疫蛋白酶体(4,5)。PSMB7由IFN-γ在蛋白水平小调，并由PSMB10/MECL-1取代，为了改变蛋白酶体的蛋白水解特异性，从而为内源性抗原提供适当的免疫处理(6)。研究者已经证实PSMB7的表达在人结肠腺癌中上调，此外，研究表明高表达的PSMB7可能作为乳腺癌愈后标志(7,8)。

1. Finley, D. (2009) Annu Rev Biochem 78, 477-513.
2. Lee, M.J. et al. (2011) Mol Cell Proteomics 10, R110.003871.
3. Stringer, J.R. et al. (1977) J Virol 21, 889-901.
4. Boes, B. et al. (1994) J Exp Med 179, 901-9.
5. Cardozo, C. and Kohanski, R.A. (1998) J Biol Chem 273, 16764-70.
6. Hisamatsu, H. et al. (1996) J Exp Med 183, 1807-16.
7. Rho, J.H. et al. (2008) J Proteome Res 7, 2959-72.
8. Munkácsy, G. et al. (2010) Br J Cancer 102, 361-8.

原厂资料：

Specificity / Sensitivity

PSMB7 (E1L5H) Rabbit mAb recognizes endogenous levels of total PSMB7 protein. This antibody reacts with precursor and mature forms of PSMB7, but does not cross-react with PSMB10.

Source / Purification

Monoclonal antibody is produced by immunizing animals with a synthetic peptide corresponding to residues surrounding Lys237 of human PSMB7 protein.

Background

The 26S proteasome is a highly abundant, ~2 MDa complex that serves as the proteolytic arm of the ubiquitin-proteasome system. It consists largely of two sub-complexes, the 19S regulatory particle (RP) and the 20S catalytic core particle (CP); in many cases two RPs cap either end of a CP. The CP is made of two stacked β-rings that contain the catalytic sites, each of which is made of seven subunits (β_1-7), flanked on either side by two α-rings, which are also made of seven subunits each (α_1-7). Thus, the structure of the 20S CP is α_1-7β_1-7β_1-7α_1-7. The RP includes a base and a lid. The base, in part, is composed of a hexametric ring of ATPases that function to unfold the substrate and open the gate of the interlacing amino-terminal segments of the α-subunits, thus allowing entry of the unfolded substrate into the catalytic chamber. The lid is predominantly involved in specific recognition of the ubiquitin signal (1). In addition to the 19S cap, other proteins and complexes, such as proteasome activator 28 (PA28/11S), bind to the end of the 20S cylinder and activate it by facilitating opening of the gate. Furthermore, proteasome-associated DUBs and E3s can remodel substrate-anchored polyubiquitin chains, which may modulate their susceptibility to degradation (2).he core particle exhibits three distinct enzymatic activities, each catalyzed by a separate protein subunit. The constitutively expressed PSMB5, PSMB7, and PSMB6 subunits provide chymotrypsin-like, trypsin-like, and caspase-like activities, respectively. These catalytic subunits belong to the amino-terminal nucleophile (Ntn) hydrolase family and are characterized by a single-residue active site. The catalytic β-subunits are synthesized with amino-terminal propeptides, which are removed at the final step of proteasome biogenesis to expose the catalytic threonine residues (3). In immune cells involved in antigen presentation, the constitutively expressed PSMB6, PSMB7, and PSMB5 subunits are replaced by three highly homologous, induced β-subunits to form the immunoproteasome (4,5). PSMB7 is downregulated at the protein level by IFN-γ and replaced by PSMB10 to remodel the proteolytic specificity of the proteasome for more appropriate immunological processing of endogenous antigens (6). Research studies show that PSMB7 expression is upregulated in human colon adenocarcinomas and suggest that high PSMB7 expression may serve as a potential prognostic marker in breast cancer (7,8).

1. Finley, D. (2009) Annu Rev Biochem 78, 477-513.
2. Lee, M.J. et al. (2011) Mol Cell Proteomics 10, R110.003871.
3. Stringer, J.R. et al. (1977) J Virol 21, 889-901.
4. Boes, B. et al. (1994) J Exp Med 179, 901-9.
5. Cardozo, C. and Kohanski, R.A. (1998) J Biol Chem 273, 16764-70.
6. Hisamatsu, H. et al. (1996) J Exp Med 183, 1807-16.
7. Rho, J.H. et al. (2008) J Proteome Res 7, 2959-72.
8. Munkácsy, G. et al. (2010) Br J Cancer 102, 361-8.

注意事项：

Storage: Supplied in 10 mM sodium HEPES (pH 7.5), 150
mM NaCl, 100 µg/ml BSA, 50% glycerol and less than 0.02%
sodium azide. Store at –20°C. Do not aliquot the antibody.