Bot1p is required for mitochondrial translation, respiratory function, and normal cell morphology in the fission yeast Schizosaccharomyces pombe.
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Bot1p is a novel S. pombe protein related to the S. cerevisiae mitoribosomal small-subunit protein MrpS35p (Rsm26p / mS42 family); it localizes to the mitochondria in live cells and cofractionates with purified mitochondrial ribosomes, establishing membership in the mitochondrial small ribosomal subunit.
"Bot1p localizes to the mitochondria in live cells and cofractionates with purified mitochondrial ribosomes."
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bot1 is essential for viability; reduced Bot1p levels cause decreased mitochondrial protein translation and correspondingly decreased cell respiration, establishing a required role in mitochondrial translation.
"Reduced levels of Bot1p lead to mitochondrial fragmentation, decreased mitochondrial protein translation, and a corresponding decrease in cell respiration."
Gene Ontology annotation through association of InterPro records with GO terms
Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Automatic assignment of GO terms using logical inference, based on inter-ontology links
UniProtKB entry O74379 (RT26_SCHPO) — Small ribosomal subunit protein mS42
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UniProt classifies the protein as "Small ribosomal subunit protein mS42" belonging to the "mitochondrion-specific ribosomal protein mS42 family", localized to the mitochondrion, forming a dimer with mS43 at the mRNA channel exit in the mt-SSU body. No superoxide dismutase / oxidoreductase / metal-binding functional annotation is claimed at the protein level; only fold-level InterPro / SUPFAM / Gene3D matches to the Fe/Mn-SOD structural superfamily are recorded.
"RecName: Full=Small ribosomal subunit protein mS42 ... FUNCTION: Component of the mitochondrial ribosome (mitoribosome), a dedicated translation machinery responsible for the synthesis of mitochondrial genome-encoded proteins ... SUBUNIT: Component of the mitochondrial small ribosomal subunit (mt-SSU) ... mS43 forms a dimer with mS42, building a large protuberance adjacent to the mRNA channel exit in the mt-SSU body ... SIMILARITY: Belongs to the mitochondrion-specific ribosomal protein mS42 family ... KW Mitochondrion; Reference proteome; Ribonucleoprotein; Ribosomal protein."
SPBC3H7.04 (mS42 / bot1) — S. pombe mitoribosomal small subunit protein
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RSM26/mS42 (SPBC3H7.04) is structurally classified in the SOD superfamily but does not have SOD activity — a fold-reuse situation driven by the bacterial ancestry of the mitochondrion. The upstream curator issue (geneontology/go-annotation#6474) diagnoses this as the reason IPR019832 should not blanket-propagate SOD activity terms; the mitoribosomal subfamily is a documented exception. Notes file reproduces the ValWood quote verbatim and contextualizes it against UniProt and PANTHER subfamily evidence.
"structurally classified in the SOD superfamily"