Cross-presentation of soluble exogenous antigens (endosomes) / Regulation of ornithine decarboxylase (ODC) / spermatoproteasome complex / Activation of NF-kappaB in B cells / Autodegradation of Cdh1 by Cdh1:APC/C / APC/C:Cdc20 mediated degradation of Securin / APC/C:Cdh1 mediated degradation of Cdc20 and other APC/C:Cdh1 targeted proteins in late mitosis/early G1 / Cdc20:Phospho-APC/C mediated degradation of Cyclin A / SCF(Skp2)-mediated degradation of p27/p21 / FCERI mediated NF-kB activation ...Cross-presentation of soluble exogenous antigens (endosomes) / Regulation of ornithine decarboxylase (ODC) / spermatoproteasome complex / Activation of NF-kappaB in B cells / Autodegradation of Cdh1 by Cdh1:APC/C / APC/C:Cdc20 mediated degradation of Securin / APC/C:Cdh1 mediated degradation of Cdc20 and other APC/C:Cdh1 targeted proteins in late mitosis/early G1 / Cdc20:Phospho-APC/C mediated degradation of Cyclin A / SCF(Skp2)-mediated degradation of p27/p21 / FCERI mediated NF-kB activation / Autodegradation of the E3 ubiquitin ligase COP1 / Asymmetric localization of PCP proteins / Degradation of AXIN / Degradation of DVL / Hedgehog ligand biogenesis / Dectin-1 mediated noncanonical NF-kB signaling / CLEC7A (Dectin-1) signaling / Degradation of GLI1 by the proteasome / Hedgehog 'on' state / TNFR2 non-canonical NF-kB pathway / NIK-->noncanonical NF-kB signaling / Assembly of the pre-replicative complex / Orc1 removal from chromatin / CDK-mediated phosphorylation and removal of Cdc6 / G2/M Checkpoints / Ubiquitin Mediated Degradation of Phosphorylated Cdc25A / Ubiquitin-dependent degradation of Cyclin D / FBXL7 down-regulates AURKA during mitotic entry and in early mitosis / RUNX1 regulates transcription of genes involved in differentiation of HSCs / Regulation of RUNX2 expression and activity / Regulation of RUNX3 expression and activity / Regulation of PTEN stability and activity / Interleukin-1 signaling / KEAP1-NFE2L2 pathway / GSK3B and BTRC:CUL1-mediated-degradation of NFE2L2 / Oxygen-dependent proline hydroxylation of Hypoxia-inducible Factor Alpha / Degradation of beta-catenin by the destruction complex / Neddylation / Antigen processing: Ubiquitination & Proteasome degradation / UCH proteinases / ABC-family proteins mediated transport / Ub-specific processing proteases / Downstream TCR signaling / The role of GTSE1 in G2/M progression after G2 checkpoint / Separation of Sister Chromatids / AUF1 (hnRNP D0) binds and destabilizes mRNA / GLI3 is processed to GLI3R by the proteasome / MAPK6/MAPK4 signaling / proteasome core complex / Neutrophil degranulation / immune system process / fat cell differentiation / antigen processing and presentation / proteasome endopeptidase complex / proteasome core complex, beta-subunit complex / proteasome core complex, alpha-subunit complex / threonine-type endopeptidase activity / negative regulation of inflammatory response to antigenic stimulus / ciliary basal body / proteolysis involved in protein catabolic process / lipopolysaccharide binding / P-body / postsynapse / proteasome-mediated ubiquitin-dependent protein catabolic process / endopeptidase activity / centrosome / synapse / mitochondrion / nucleoplasm / identical protein binding / nucleus / cytoplasm / cytosol 類似検索 - 分子機能
ジャーナル: Nat Commun / 年: 2021 タイトル: Cryo-EM of mammalian PA28αβ-iCP immunoproteasome reveals a distinct mechanism of proteasome activation by PA28αβ. 著者: Jinhuan Chen / Yifan Wang / Cong Xu / Kaijian Chen / Qiaoyu Zhao / Shutian Wang / Yue Yin / Chao Peng / Zhanyu Ding / Yao Cong / 要旨: The proteasome activator PA28αβ affects MHC class I antigen presentation by associating with immunoproteasome core particles (iCPs). However, due to the lack of a mammalian PA28αβ-iCP structure, ...The proteasome activator PA28αβ affects MHC class I antigen presentation by associating with immunoproteasome core particles (iCPs). However, due to the lack of a mammalian PA28αβ-iCP structure, how PA28αβ regulates proteasome remains elusive. Here we present the complete architectures of the mammalian PA28αβ-iCP immunoproteasome and free iCP at near atomic-resolution by cryo-EM, and determine the spatial arrangement between PA28αβ and iCP through XL-MS. Our structures reveal a slight leaning of PA28αβ towards the α3-α4 side of iCP, disturbing the allosteric network of the gatekeeper α2/3/4 subunits, resulting in a partial open iCP gate. We find that the binding and activation mechanism of iCP by PA28αβ is distinct from those of constitutive CP by the homoheptameric TbPA26 or PfPA28. Our study sheds lights on the mechanism of enzymatic activity stimulation of immunoproteasome and suggests that PA28αβ-iCP has experienced profound remodeling during evolution to achieve its current level of function in immune response.