{"uniprot":"Q5JNZ5","gene":"RPS26P11","name":"Putative 40S ribosomal protein S26-like 1","organism":"Homo sapiens (Human)","status":"dark","length":115,"sequence":"MTKKRRNNSHAKKGRGHVQPIRCTNCVRCVPTDKAIKKFVIRNIVEAAAVRDISEVSVFDAYVLPKLYVKLHYCVSCAIHSKVVRNRSREACKDRTPPPRFRPAGAAPRPPPKPM","function_summary":"A cytoplasmic component of the small ribosomal subunit that stabilizes the architecture of translating ribosomes and supports mRNA engagement during cytoplasmic protein synthesis. It assembles into polysomes and participates in ribosome biogenesis and function, with transient nucleoplasmic shuttling that can interface with RNA-processing pathways. Peripheral associations near membranes and within extracellular vesicles likely reflect ribosome docking and packaging, and a moonlighting surface may transiently engage cadherin-containing assemblies.","plain_language":"RPS26P11 has barely been studied. The model's best guess: A cytoplasmic component of the small ribosomal subunit that stabilizes the architecture of translating ribosomes and supports mRNA engagement during cytoplasmic protein synthesis. It assembles into polysomes and participates in ribosome biogenesis and function, with transient nucleoplasmic shuttling that can interface with RNA-processing pathways.","uniprot_summary":"Component of the 40S small ribosomal subunit.","go_terms":{"molecular_function":[{"id":"GO:0003735","label":"structural constituent of ribosome"},{"id":"GO:0045296","label":"cadherin binding"},{"id":"GO:0003729","label":"mRNA binding"}],"biological_process":[{"id":"GO:0033119","label":"negative regulation of RNA splicing"},{"id":"GO:0002181","label":"cytoplasmic translation"}],"cellular_component":[{"id":"GO:0016020","label":"membrane"},{"id":"GO:0005829","label":"cytosol"},{"id":"GO:0005654","label":"nucleoplasm"},{"id":"GO:0005844","label":"polysome"},{"id":"GO:0070062","label":"extracellular exosome"},{"id":"GO:0022627","label":"cytosolic small ribosomal subunit"},{"id":"GO:0042788","label":"polysomal ribosome"}]},"interpro":[{"id":"IPR038551","name":"Ribosomal protein eS26 superfamily","type":"homologous_superfamily","start":1,"end":115},{"id":"IPR000892","name":"Small ribosomal subunit protein eS26","type":"family","start":1,"end":115},{"id":"IPR047864","name":"Ribosomal protein eS26, conserved site","type":"conserved_site","start":73,"end":80}],"reasoning":"I begin with the InterPro architecture. The sequence is fully covered by IPR000892 (Small ribosomal subunit protein eS26 family, residues 1–115) and by the broader IPR038551 (Ribosomal protein eS26 superfamily, residues 1–115), indicating a canonical eukaryotic small-subunit ribosomal protein that forms part of the 40S particle. Within this scaffold, IPR047864 marks a conserved site at residues 73–80, a motif typical of eS26 that stabilizes RNA contacts and subunit assembly. The complete coverage by ribosomal family and superfamily signatures, together with a conserved internal patch, defines a structural role rather than enzymatic catalysis.\n\nThis architecture causes the molecular function of a structural constituent of ribosomes (GO:0003735). The eS26 fold and conserved site support direct RNA engagement, consistent with mRNA binding (GO:0003729) during initiation and elongation on translating ribosomes. The presence of cadherin binding (GO:0045296) suggests an auxiliary, moonlighting interface that can transiently associate with cadherin-containing complexes; such peripheral interactions can arise when ribosomes dock near membrane-proximal translation sites or when ribosomal proteins are trafficked in extracellular vesicles.\n\nFrom these molecular activities, the biological processes follow. As a core 40S component, eS26 directly supports cytoplasmic translation (GO:0002181) by stabilizing the mRNA–ribosome interface and sustaining polysome formation. Its nucleoplasmic presence and coupling to RNA-processing hubs rationalize negative regulation of RNA splicing (GO:0033119): ribosome-associated factors often shuttle through the nucleoplasm, where eS26 can modulate spliceosomal dynamics indirectly through RNA-bound assemblies.\n\nCellular localization is multifaceted. The primary residence is the cytoplasm, aligning with the experimentally supported cytoplasmic localization and with occupancy of the cytosolic small ribosomal subunit (GO:0022627) and polysomal ribosome (GO:0042788). Transit through the nucleoplasm (GO:0005654) is explained by ribosome biogenesis and RNA-processing interfaces. Association with membrane (GO:0016020) is consistent with polysome docking at membrane-proximal translation sites and with packaging into extracellular exosomes (GO:0070062), which frequently carry ribosomal proteins and polysomes.\n\nMechanistically, eS26 stabilizes the 40S head and contributes to mRNA engagement and polysome assembly. It likely interacts with neighboring small-subunit proteins and initiation factors to position mRNA and tRNA. Peripheral interactions with cadherin-associated complexes and membrane-proximal translation sites may explain its membrane and exosome associations. I hypothesize that eS26 partners with other 40S proteins and initiation machinery to drive efficient cytoplasmic translation, while transient nucleoplasmic shuttling enables crosstalk with RNA splicing pathways.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-Q5JNZ5.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/Q5JNZ5"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/Q5JNZ5/entry","atlas":"/p/Q5JNZ5"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}