4v8t
From Proteopedia
Cryo-EM Structure of the 60S Ribosomal Subunit in Complex with Arx1 and Rei1
Structural highlights
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Function[RL25_YEAST] This protein binds to a specific region on the 26S rRNA. [RL11B_YEAST] Binds to 5S ribosomal RNA. [RL401_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).[1] 60S ribosomal protein L40: component of the 60S subunit of the ribosome. Ribosomal protein L40 is essential for translation of a subset of cellular transcripts, including stress response transcripts, such as DDR2.[2] [RL37A_YEAST] Binds to the 23S rRNA (By similarity). [RL4A_YEAST] Participates in the regulation of the accumulation of its own mRNA.[3] [RL5_YEAST] Binds 5S RNA and is required for 60S subunit assembly. [RLA0_YEAST] Ribosomal protein P0 is the functional equivalent of E.coli protein L10. Publication Abstract from PubMedEukaryotic ribosome biogenesis requires many protein factors that facilitate the assembly, nuclear export and final maturation of 40S and 60S particles. We have biochemically characterized ribosomal complexes of the yeast 60S-biogenesis factor Arx1 and late-maturation factors Rei1 and Jjj1 and determined their cryo-EM structures. Arx1 was visualized bound to the 60S subunit together with Rei1, at 8.1-A resolution, to reveal the molecular details of Arx1 binding whereby Arx1 arrests the eukaryotic-specific rRNA expansion segment 27 near the polypeptide tunnel exit. Rei1 and Jjj1, which have been implicated in Arx1 recycling, bind in the vicinity of Arx1 and form a network of interactions. We suggest that, in addition to the role of Arx1 during pre-60S nuclear export, the binding of Arx1 conformationally locks the pre-60S subunit and inhibits the premature association of nascent chain-processing factors to the polypeptide tunnel exit. Cryo-EM structures of Arx1 and maturation factors Rei1 and Jjj1 bound to the 60S ribosomal subunit.,Greber BJ, Boehringer D, Montellese C, Ban N Nat Struct Mol Biol. 2012 Nov 11. doi: 10.1038/nsmb.2425. PMID:23142985[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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