View source for 8cxb


==Human PA28-20S (PA28-4a3b)==
<StructureSection load='8cxb' size='340' side='right'caption='[[8cxb]], [[Resolution|resolution]] 2.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8cxb]] is a 23 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8CXB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8CXB FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 2.9&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=8cxb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8cxb OCA], [https://pdbe.org/8cxb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8cxb RCSB], [https://www.ebi.ac.uk/pdbsum/8cxb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8cxb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/PSME2_HUMAN PSME2_HUMAN] Implicated in immunoproteasome assembly and required for efficient antigen processing. The PA28 activator complex enhances the generation of class I binding peptides by altering the cleavage pattern of the proteasome.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The ability to produce folded and functional proteins is a necessity for structural biology and many other biological sciences. This task is particularly challenging for numerous biomedically important targets in human cells, including membrane proteins and large macromolecular assemblies, hampering mechanistic studies and drug development efforts. Here we describe a method combining CRISPR-Cas gene editing and fluorescence-activated cell sorting to rapidly tag and purify endogenous proteins in HEK cells for structural characterization. We applied this approach to study the human proteasome from HEK cells and rapidly determined cryogenic electron microscopy structures of major proteasomal complexes, including a high-resolution structure of intact human PA28alphabeta-20S. Our structures reveal that PA28 with a subunit stoichiometry of 3alpha/4beta engages tightly with the 20S proteasome. Addition of a hydrophilic peptide shows that polypeptides entering through PA28 are held in the antechamber of 20S prior to degradation in the proteolytic chamber. This study provides critical insights into an important proteasome complex and demonstrates key methodologies for the tagging of proteins from endogenous sources.

Structural insights into the human PA28-20S proteasome enabled by efficient tagging and purification of endogenous proteins.,Zhao J, Makhija S, Zhou C, Zhang H, Wang Y, Muralidharan M, Huang B, Cheng Y Proc Natl Acad Sci U S A. 2022 Aug 16;119(33):e2207200119. doi: , 10.1073/pnas.2207200119. Epub 2022 Jul 19. PMID:35858375<ref>PMID:35858375</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 8cxb" style="background-color:#fffaf0;"></div>

==See Also==
*[[Proteasome 3D structures|Proteasome 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Cheng Y]]
[[Category: Huang B]]
[[Category: Makhija S]]
[[Category: Zhao J]]