View source for 9rsx


==Structure of RACK1 bound to the C-terminus of SERBP1 and the RIH region of ZAK==
<StructureSection load='9rsx' size='340' side='right'caption='[[9rsx]], [[Resolution|resolution]] 2.91&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9rsx]] is a 4 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=9RSX OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9RSX 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]] 2.91&#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=9rsx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9rsx OCA], [https://pdbe.org/9rsx PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9rsx RCSB], [https://www.ebi.ac.uk/pdbsum/9rsx PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9rsx ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/M3K20_HUMAN M3K20_HUMAN] Split-foot malformation-mesoaxial polydactyly syndrome;Congenital fiber-type disproportion myopathy. The disease is caused by variants affecting the gene represented in this entry.  The disease is caused by variants affecting the gene represented in this entry.
== Function ==
[https://www.uniprot.org/uniprot/M3K20_HUMAN M3K20_HUMAN] Stress-activated component of a protein kinase signal transduction cascade that promotes programmed cell death in response to various stress, such as ribosomal stress, osmotic shock and ionizing radiation (PubMed:10924358, PubMed:11836244, PubMed:12220515, PubMed:14521931, PubMed:15350844, PubMed:15737997, PubMed:18331592, PubMed:20559024, PubMed:26999302, PubMed:32289254, PubMed:32610081, PubMed:35857590). Acts by catalyzing phosphorylation of MAP kinase kinases, leading to activation of the JNK (MAPK8/JNK1, MAPK9/JNK2 and/or MAPK10/JNK3) and MAP kinase p38 (MAPK11, MAPK12, MAPK13 and/or MAPK14) pathways (PubMed:11042189, PubMed:11836244, PubMed:12220515, PubMed:14521931, PubMed:15172994, PubMed:15737997, PubMed:32289254, PubMed:32610081, PubMed:35857590). Activates JNK through phosphorylation of MAP2K4/MKK4 and MAP2K7/MKK7, and MAP kinase p38 gamma (MAPK12) via phosphorylation of MAP2K3/MKK3 and MAP2K6/MKK6 (PubMed:11836244, PubMed:12220515). Involved in stress associated with adrenergic stimulation: contributes to cardiac decompensation during periods of acute cardiac stress (PubMed:15350844, PubMed:21224381, PubMed:27859413). May be involved in regulation of S and G2 cell cycle checkpoint by mediating phosphorylation of CHEK2 (PubMed:15342622).<ref>PMID:10924358</ref> <ref>PMID:11042189</ref> <ref>PMID:11836244</ref> <ref>PMID:12220515</ref> <ref>PMID:14521931</ref> <ref>PMID:15172994</ref> <ref>PMID:15342622</ref> <ref>PMID:15350844</ref> <ref>PMID:15737997</ref> <ref>PMID:18331592</ref> <ref>PMID:20559024</ref> <ref>PMID:21224381</ref> <ref>PMID:26999302</ref> <ref>PMID:27859413</ref> <ref>PMID:32289254</ref> <ref>PMID:32610081</ref> <ref>PMID:35857590</ref>   Key component of the stress-activated protein kinase signaling cascade in response to ribotoxic stress or UV-B irradiation (PubMed:32289254, PubMed:32610081, PubMed:35857590). Acts as the proximal sensor of ribosome collisions during the ribotoxic stress response (RSR): directly binds to the ribosome by inserting its flexible C-terminus into the ribosomal intersubunit space, thereby acting as a sentinel for colliding ribosomes (PubMed:32289254, PubMed:32610081). Upon ribosome collisions, activates either the stress-activated protein kinase signal transduction cascade or the integrated stress response (ISR), leading to programmed cell death or cell survival, respectively (PubMed:32610081). Dangerous levels of ribosome collisions trigger the autophosphorylation and activation of MAP3K20, which dissociates from colliding ribosomes and phosphorylates MAP kinase kinases, leading to activation of the JNK and MAP kinase p38 pathways that promote programmed cell death (PubMed:32289254, PubMed:32610081). Less dangerous levels of ribosome collisions trigger the integrated stress response (ISR): MAP3K20 activates EIF2AK4/GCN2 independently of its protein-kinase activity, promoting EIF2AK4/GCN2-mediated phosphorylation of EIF2S1/eIF-2-alpha (PubMed:32610081). Also part of the stress-activated protein kinase signaling cascade triggering the NLRP1 inflammasome in response to UV-B irradiation: ribosome collisions activate MAP3K20, which directly phosphorylates NLRP1, leading to activation of the NLRP1 inflammasome and subsequent pyroptosis (PubMed:35857590). NLRP1 is also phosphorylated by MAP kinase p38 downstream of MAP3K20 (PubMed:35857590). Also acts as a histone kinase by phosphorylating histone H3 at 'Ser-28' (H3S28ph) (PubMed:15684425).<ref>PMID:15684425</ref> <ref>PMID:32289254</ref> <ref>PMID:32610081</ref> <ref>PMID:35857590</ref>   Isoform that lacks the C-terminal region that mediates ribosome-binding: does not act as a sensor of ribosome collisions in response to ribotoxic stress (PubMed:32289254, PubMed:32610081, PubMed:35857590). May act as an antagonist of isoform ZAKalpha: interacts with isoform ZAKalpha, leading to decrease the expression of isoform ZAKalpha (PubMed:27859413).<ref>PMID:27859413</ref> <ref>PMID:32289254</ref> <ref>PMID:32610081</ref> <ref>PMID:35857590</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Ribosome collisions activate the ribotoxic stress response mediated by the MAP3K ZAK, which in turn regulates cell-fate consequences through downstream phosphorylation of the MAPKs p38 and JNK(1). Despite the critical role of ZAK during cellular stress, a mechanistic and structural understanding of ZAK-ribosome interactions and how these lead to activation remain elusive. Here we combine biochemistry and cryo-electron microscopy to discover distinct ZAK-ribosome interactions required for constitutive recruitment and for activation. We find that upon induction of ribosome collisions, interactions between ZAK and the ribosomal protein RACK1 enable its activation by dimerization of its SAM domains at the collision interface. Furthermore, we discover how this process is negatively regulated by the ribosome-binding protein SERBP1 to prevent constitutive ZAK activation. Characterization of novel SAM variants as well as a known pathogenic variant of the SAM domain of ZAK supports a key role of the SAM domain in regulating kinase activity on and off the ribosome, with some mutants bypassing the ribosome requirement for ZAK activation. Collectively, our data provide a mechanistic blueprint of the kinase activity of ZAK at the collided ribosome interface.

ZAK activation at the collided ribosome.,Huso VL, Niu S, Catipovic MA, Saba JA, Denk T, Park E, Cheng J, Berninghausen O, Becker T, Green R, Beckmann R Nature. 2025 Nov 19. doi: 10.1038/s41586-025-09772-8. PMID:41261136<ref>PMID:41261136</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9rsx" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Beckmann R]]
[[Category: Niu S]]