{"uniprot":"A6NJG2","gene":"SOWAHD","name":"Ankyrin repeat domain-containing protein SOWAHD","organism":"Homo sapiens (Human)","status":"dark","length":315,"sequence":"MAQLGGAANRAPTASLAPTSQSLRCAPQPRPSRADTGSLGRYWGKAAAAASREHPFPGTLMHSAAGSGRRRGALRELLGLQRAAPAGWLSEERAEELGGPSGPGSSRLCLEPREHAWILAAAEGRYEVLRELLEAEPELLLRGDPITGYSVLHWLAKHGRHEELILVHDFALRRGLRLDVSAPGSGGLTPLHLAALQGHDMVIKVLVGALGADATRRDHSGHRACHYLRPDAPWRLRELSGAEEWEMESGSGCTNLNNNSSGTTAWRAASAVGATAVETSRRVAASRTKAKDTAGSRVAQMHSLFRHLFPSFQDR","function_summary":"A nucleoplasmic scaffold that uses an ankyrin-repeat array to assemble transcriptional complexes. By stabilizing interactions among transcription factors, coactivators, and RNA polymerase II, it enhances transcriptional output from active chromatin. Its soluble architecture and association with nucleic acids position it within the nuclear interior, where it promotes transcriptional activation through multivalent protein binding and recruitment of chromatin-modifying and elongation machinery.","plain_language":"SOWAHD has barely been studied. The model's best guess: A nucleoplasmic scaffold that uses an ankyrin-repeat array to assemble transcriptional complexes. By stabilizing interactions among transcription factors, coactivators, and RNA polymerase II, it enhances transcriptional output from active chromatin.","uniprot_summary":"Binds nucleic acids. May be involved in transcriptional regulation.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0045944","label":"positive regulation of transcription by RNA polymerase II"}],"cellular_component":[{"id":"GO:0005654","label":"nucleoplasm"}]},"interpro":[{"id":"IPR036770","name":"Ankyrin repeat-containing domain superfamily","type":"homologous_superfamily","start":91,"end":232},{"id":"IPR002110","name":"Ankyrin repeat","type":"repeat","start":112,"end":218}],"reasoning":"I begin with the InterPro architecture. The core of the protein is an ankyrin-repeat scaffold: IPR036770 (Ankyrin repeat-containing domain superfamily, residues 91–232) encompasses a tandem repeat array that is explicitly annotated by IPR002110 (Ankyrin repeat, residues 112–218). Ankyrin repeats form elongated, solenoid-like surfaces that specialize in high-specificity, moderate-affinity protein–protein interactions. The ordered placement of the ankyrin superfamily region downstream of an N-terminal segment and its concentration in the central portion of the polypeptide creates a multivalent binding platform. This architecture causally dictates a molecular function centered on protein binding (GO:0005515), rather than catalysis.\n\nFrom this binding-centric core, I infer the biological role by considering where such scaffolds operate and to whom they bind. Ankyrin-repeat transcriptional regulators commonly assemble transcriptional complexes by docking transcription factors, coactivators, and chromatin remodelers. The explicit evidence of nucleic-acid association—suggesting a role in nucleic acid handling—combined with a soluble ankyrin scaffold points toward assembly rather than direct catalysis or stable DNA/RNA binding. This scaffolding capacity provides a mechanistic route to positive regulation of transcription by RNA polymerase II (GO:0045944): by recruiting and stabilizing transcriptional activators and coactivator modules at promoters and enhancers, the protein increases transcriptional output.\n\nCellular localization follows from function and architecture. The absence of transmembrane features and the soluble ankyrin-repeat fold support a non-membranous compartment. Positive regulation of Pol II transcription and nucleic-acid association place the complex within the nuclear interior, specifically the nucleoplasm (GO:0005654), where transcription factories and chromatin-modifying assemblies reside. This nucleoplasmic residency aligns with the broader nuclear localization and provides the spatial context for assembling transcriptional machinery.\n\nMechanistically, I hypothesize that the ankyrin-repeat array nucleates a nucleoplasmic hub that bridges sequence-specific transcription factors and coactivators to RNA polymerase II and associated elongation factors. By stabilizing these assemblies at active chromatin, the scaffold enhances initiation and productive elongation. Likely partners include Pol II core subunits and Mediator components for signal integration; histone acetyltransferases and chromatin remodelers for nucleosome engagement; and RNA-processing factors that couple transcription to RNA maturation. Together, these interactions explain how a nucleic-acid-associated ankyrin-repeat scaffold drives transcriptional activation within the nucleoplasm.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-A6NJG2.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/A6NJG2"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/A6NJG2/entry","atlas":"/p/A6NJG2"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}