6rbe | pdb_00006rbe
State 2 of yeast Tsr1-TAP Rps20-Deltaloop pre-40S particles
Structural highlights
Function[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.[1] [RS31_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: Component of the ribosome, a large ribonucleoprotein complex responsible for the synthesis of proteins in the cell. The small ribosomal subunit (SSU) binds messenger RNAs (mRNAs) and translates the encoded message by selecting cognate aminoacyl-transfer RNA (tRNA) molecules. The large subunit (LSU) contains the ribosomal catalytic site termed the peptidyl transferase center (PTC), which catalyzes the formation of peptide bonds, thereby polymerizing the amino acids delivered by tRNAs into a polypeptide chain. The nascent polypeptides leave the ribosome through a tunnel in the LSU and interact with protein factors that function in enzymatic processing, targeting, and the membrane insertion of nascent chains at the exit of the ribosomal tunnel.[2] [RS7A_YEAST] Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly.[3] [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.[4] [5] [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). [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] [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.[6] [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.[7] [8] [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.[9] [RS6A_YEAST] Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly.[10] [RS9A_YEAST] Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly.[11] [RS14A_YEAST] Involved in nucleolar processing of pre-18S ribosomal RNA and ribosome assembly.[12] [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.[13] Publication Abstract from PubMedEukaryotic ribosomes are synthesized in a hierarchical process driven by a plethora of assembly factors, but how maturation events at physically distant sites on pre-ribosomes are coordinated is poorly understood. Using functional analyses and cryo-EM, we show that ribosomal protein Rps20 orchestrates communication between two multi-step maturation events across the pre-40S subunit. Our study reveals that during pre-40S maturation, formation of essential contacts between Rps20 and Rps3 permits assembly factor Ltv1 to recruit the Hrr25 kinase, thereby promoting Ltv1 phosphorylation. In parallel, a deeply buried Rps20 loop reaches to the opposite pre-40S side, where it stimulates Rio2 ATPase activity. Both cascades converge to the final maturation steps releasing Rio2 and phosphorylated Ltv1. We propose that conformational proofreading exerted via Rps20 constitutes a checkpoint permitting assembly factor release and progression of pre-40S maturation only after completion of all earlier maturation steps. Conformational proofreading of distant 40S ribosomal subunit maturation events by a long-range communication mechanism.,Mitterer V, Shayan R, Ferreira-Cerca S, Murat G, Enne T, Rinaldi D, Weigl S, Omanic H, Gleizes PE, Kressler D, Plisson-Chastang C, Pertschy B Nat Commun. 2019 Jun 21;10(1):2754. doi: 10.1038/s41467-019-10678-z. PMID:31227701[14] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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