6fai

Structure of a eukaryotic cytoplasmic pre-40S ribosomal subunit

Loading... Status: waiting for Mol* initialization Structural highlights 6fai is a 36 chain structure with sequence from Baker's yeast and Saccharomyces cerevisiae (strain atcc 204508 / s288c). Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: MG, ZN Activity: Non-specific serine/threonine protein kinase, with EC number 2.7.11.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [RS21A_YEAST] Required for the processing of the 20S rRNA-precursor to mature 18S rRNA in a late step of the maturation of 40S ribosomal subunits. Has a physiological role leading to 18S rRNA stability. [RS9A_YEAST] Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly. [ENP1_YEAST] Required for normal export of the pre-40S particles from the nucleus to the cytoplasm. Its subcellular location and association with pre-40S subunit shifts from mixed cytoplasm/nucleus to all nuclear in RPS19 disruptions, suggesting it acts after the ribosomal protein. [RS15_YEAST] Involved in the nuclear export of the small ribosomal subunit. Has a role in the late stage of the assembly of pre-40S particles within the nucleus and controls their export to the cytoplasm. [RS27A_YEAST] Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, and DNA-damage responses. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling (By similarity). 40S ribosomal protein S31 is a component of the 40S subunit of the ribosome (By similarity). [RS6A_YEAST] Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly. [RS19A_YEAST] Required for proper maturation of the small (40S) ribosomal subunit. Binds to 40s pre-ribosomal particles, probably required after association of NOC4 but before association of ENP1, TSR1 and RIO2 with 20/21S pre-rRNA. [RS14A_YEAST] Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly. [RS2_YEAST] Important in the assembly and function of the 40S ribosomal subunit. Mutations in this protein affects the control of translational fidelity. Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly. [RIO2_YEAST] Required for the final endonucleolytic cleavage of 20S pre-rRNA at site D in the cytoplasm, converting it into the mature 18S rRNA. Involved in normal export of the pre-40S particles from the nucleus to the cytoplasm. No longer associates with pre-40S subunits in RPS19 disruptions, suggesting it acts after the ribosomal protein in 18S rRNA maturation. [RS18A_YEAST] Located at the top of the head of the 40S subunit, it contacts several helices of the 18S rRNA (By similarity).[HAMAP-Rule:MF_01315] [PNO1_YEAST] Required for small ribosomal subunit (SSU) synthesis. Has a role in the processing of early nucleolar and late cytoplasmic pre-RNA species. Recruits DIM1 to nucleolar pre-RNAs. Indirectly required for cleavage at the A2 site of the 20S pre-rRNA, forming 18S rRNA, and at A1 and A2 sites of other pre-rRNAs. [TSR1_YEAST] Required for 40S ribosomal subunit synthesis. Required for normal export of the pre-40S particles from the nucleus to the cytoplasm. Its subcellular location and association with pre-40S subunitshifts from mixed cytoplasm/nucleus to all nuclear in RPS19 disruptions, suggesting it acts after the ribosomal protein. [RSSA1_YEAST] Required for the assembly and/or stability of the 40S ribosomal subunit. Required for the processing of the 20S rRNA-precursor to mature 18S rRNA in a late step of the maturation of 40S ribosomal subunits. [LTV1_YEAST] Involved in protein transport. Non-ribosomal factor required for efficient nuclear export of the ribosomal 40S subunit. Component of the GSE complex, a GTPase complex required for intracellular sorting of GAP1 out of the endosome. [RS7A_YEAST] Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly. [GBLP_YEAST] Located at the head of the 40S ribosomal subunit in the vicinity of the mRNA exit channel, it serves as a scaffold protein that can recruit other proteins to the ribosome. Involved in the negative regulation of translation of a specific subset of proteins. Publication Abstract from PubMed Final maturation of eukaryotic ribosomes occurs in the cytoplasm and requires the sequential removal of associated assembly factors and processing of the immature 20S pre-RNA Using cryo-electron microscopy (cryo-EM), we have determined the structure of a yeast cytoplasmic pre-40S particle in complex with Enp1, Ltv1, Rio2, Tsr1, and Pno1 assembly factors poised to initiate final maturation. The structure reveals that the pre-rRNA adopts a highly distorted conformation of its 3' major and 3' minor domains stabilized by the binding of the assembly factors. This observation is consistent with a mechanism that involves concerted release of the assembly factors orchestrated by the folding of the rRNA in the head of the pre-40S subunit during the final stages of maturation. Our results provide a structural framework for the coordination of the final maturation events that drive a pre-40S particle toward the mature form capable of engaging in translation. Structure of a eukaryotic cytoplasmic pre-40S ribosomal subunit.,Scaiola A, Pena C, Weisser M, Bohringer D, Leibundgut M, Klingauf-Nerurkar P, Gerhardy S, Panse VG, Ban N EMBO J. 2018 Feb 19. pii: embj.201798499. doi: 10.15252/embj.201798499. PMID:29459436 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Receptor for activated protein kinase C 1 Ribosome 3D structures Ribosome biogenesis protein

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