RPL12

RPL12/uL11 is a large ribosomal subunit protein of the GTPase-associated center (GAC) that drives translation elongation by positioning the uL10/P-complex stalk to recruit incoming translational GTPases (PMID:26939941, PMID:35544198). Its eukaryote-specific, intrinsically disordered N-terminal MPPKFDP motif, together with the conserved GPLG helix-1 motif, mediates this interaction with uL10 and the P-complex, and disruption of these elements sharply reduces poly-phenylalanine synthesis (PMID:35544198). Beyond positioning the stalk, uL11 contributes broadly across the translation cycle: it participates in Tif6 release and subunit joining at initiation, mediates eEF1A interaction and decoding accuracy during elongation, and supports eEF2-dependent translocation (PMID:26939941). The protein is a hub for regulatory post-translational modifications that specialize ribosome function: mitotic CDK1 phosphorylation of Ser38 depletes RPL12 from polysomes to reprogram translation of specific mRNA subsets during mitosis (PMID:30220558), and Set domain methyltransferases (Set11) methylate uL11 at lysine 3 during ribosome assembly in the nucleolus (PMID:18195021). The K3 methyl mark also underlies an extra-ribosomal role: trimethylated uL11K3 binds the chromodomain protein Corto and co-localizes with RNA Polymerase II to fine-tune ribosomal protein gene transcription (PMID:35981051). RPL12 additionally serves as a conserved ribophagy receptor, binding Atg8 directly and, upon Atg1-mediated phosphorylation, associating with the scaffold Atg11 to trigger selective ribosome degradation during starvation (PMID:39934334).

1. 2008 High

   Established that Rpl12 carries a specific, enzymatically installed methyl mark, identifying Set11 as the methyltransferase that targets lysine 3 and linking the modification to ribosome assembly.

   Evidence In vitro methylation with recombinant Set11, 2D gel/MS substrate identification, K3 mutagenesis, and nucleolar localization in fission yeast

   PMID:18195021

   Open questions at the time

   • Functional consequence of K3 methylation for the ribosome was not defined
   • Whether methylation alters translation or assembly kinetics was untested
2. 2016 Medium

   Defined uL11 as a critical GAC element required across the translation cycle, resolving how it supports translational GTPase function rather than acting at a single step.

   Evidence Yeast single/double deletion mutants with translation fidelity, subunit joining, and GTPase interaction assays

   PMID:26939941

   Open questions at the time

   • Structural basis for GTPase positioning not resolved here
   • Single yeast model system
3. 2018 High

   Demonstrated that a post-translational modification of a core ribosomal protein generates specialized ribosomes, showing CDK1 phosphorylation of Ser38 excludes RPL12 from polysomes to gate mitotic mRNA translation.

   Evidence Polysome sucrose-gradient proteomics/phosphoproteomics plus functional translation experiments in human cells

   PMID:30220558

   Open questions at the time

   • The specific mRNA features recognized under Ser38 phosphorylation not fully defined
   • Mechanism by which phospho-RPL12 is excluded from polysomes unresolved
4. 2020 Low

   Probed a moonlighting role beyond translation, linking uL11 perturbation to altered cell-cycle progression and metabolic state.

   Evidence Yeast deletion mutants with integrated transcriptomics, metabolomics, and longevity assays

   PMID:32708309

   Open questions at the time

   • Cell-cycle claim rests on indirect omics correlations without direct pathway placement
   • Translation-dependent and extra-ribosomal contributions not separated
5. 2022 High

   Resolved the structural and mechanistic basis of uL11's elongation role, showing its flexible eukaryote-specific N-terminus positions uL10/P-complex to recruit translational GTPases.

   Evidence NMR solution structure with backbone dynamics, in vitro binding/mutagenesis, and poly-phenylalanine synthesis in hybrid and yeast ribosomes

   PMID:35544198

   Open questions at the time

   • GTPase recruitment captured in vitro; in-cell dynamics not visualized
   • How modifications (Ser38-P, K3me) affect N-terminal positioning not addressed
6. 2022 Medium

   Connected the K3 methyl mark to an extra-ribosomal transcriptional function, showing methylated uL11 engages Corto at RNA Pol II sites to tune ribosomal protein gene expression.

   Evidence CRISPR K3 mutagenesis, reciprocal co-IP, polytene co-localization, and RNA-seq in Drosophila wing discs

   PMID:35981051

   Open questions at the time

   • Whether the chromatin-associated uL11 pool is ribosome-free not established
   • Mechanism by which uL11 modulates Corto-mediated repression unclear
   • Conservation of the Corto interaction in mammals untested
7. 2025 High

   Identified RPL12 as a conserved ribophagy receptor, explaining how ribosomes are selectively delivered to autophagy during starvation.

   Evidence Atg8-binding disruption, Atg1 kinase phosphorylation assays, Rpl12–Atg11 interaction, and lifespan/phenotype analysis across yeast, C. elegans, Drosophila, and mammalian cells

   PMID:39934334

   Open questions at the time

   • The phosphosite(s) used by Atg1 and their relation to CDK1-Ser38 not delineated
   • How receptor function is partitioned from ribosome-bound uL11 unresolved

• How RPL12's distinct modifications (K3 methylation, Ser38 and Atg1 phosphorylation) are coordinated to switch between ribosomal, transcriptional, and ribophagy functions remains unresolved.
• No unified model linking the three modification states
• Whether distinct uL11 pools (ribosomal vs. extra-ribosomal vs. receptor) coexist in one cell is unknown