3j2i
From Proteopedia
Structure of late pre-60S ribosomal subunits with nuclear export factor Arx1 bound at the peptide exit tunnel
Structural highlights
Function[IF6_YEAST] Binds to the 60S ribosomal subunit and prevents its association with the 40S ribosomal subunit to form the 80S initiation complex in the cytoplasm. Is also involved in ribosome biogenesis. Associates with pre-60S subunits in the nucleus and is involved in its nuclear export. Cytoplasmic release of TIF6 from 60S subunits and nuclear relocalization is promoted by the GTPase RIA1/EFL1 and by SDO1. Also required for pre-rRNA processing.[1] [2] [3] [4] [5] [6] [PA2G4_HUMAN] May play a role in a ERBB3-regulated signal transduction pathway. Seems be involved in growth regulation. Acts a corepressor of the androgen receptor (AR) and is regulated by the ERBB3 ligand neuregulin-1/heregulin (HRG). Inhibits transcription of some E2F1-regulated promoters, probably by recruiting histone acetylase (HAT) activity. Binds RNA. Associates with 28S, 18S and 5.8S mature rRNAs, several rRNA precursors and probably U3 small nucleolar RNA. May be involved in regulation of intermediate and late steps of rRNA processing. May be involved in ribosome assembly. Mediates cap-independent translation of specific viral IRESs (internal ribosomal entry site) (By similarity).[7] [8] [9] [10] Publication Abstract from PubMedPreribosomal particles evolve in the nucleus through transient interaction with biogenesis factors before export to the cytoplasm. Here, we report the architecture of the late pre-60S particle, purified from Saccharomyces cerevisiae, through Arx1, a nuclear export factor with structural homology to methionine aminopeptidases, or its binding partner Alb1. Cryo-EM reconstruction of the Arx1 particle at 11.9-A resolution reveals regions of extra density on the pre-60S particle attributed to associated biogenesis factors, confirming the immature state of the nascent subunit. One of these densities could be unambiguously assigned to Arx1. Immunoelectron microscopy and UV cross-linking localize Arx1 close to the ribosomal exit tunnel, in direct contact with ES27, a highly dynamic eukaryotic rRNA expansion segment. The binding of Arx1 at the exit tunnel may position this export factor to prevent premature recruitment of ribosome-associated factors active during translation. Structure of the pre-60S ribosomal subunit with nuclear export factor Arx1 bound at the exit tunnel.,Bradatsch B, Leidig C, Granneman S, Gnadig M, Tollervey D, Bottcher B, Beckmann R, Hurt E Nat Struct Mol Biol. 2012 Nov 11. doi: 10.1038/nsmb.2438. PMID:23142978[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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