{"uniprot":"O95744","gene":"PMS2P2","name":"Putative postmeiotic segregation increased 2-like protein 2","organism":"Homo sapiens (Human)","status":"dark","length":297,"sequence":"MGESSRKPPTPTPEGPTVSVKQLFSTLPVRHKEFQRNIKKKRACFPFAFCRDCQFLEGSPAMLPVQPAKLTEPAKAIKPIDRKSVHQICSGPVVLSLSTAVKKIVGNSLDAGATNIDLKLKDYGMDLIEVSGNGCGVEEENFEGLSLSALKHHTSKIREFADLTRVETFGFQGKALSSLCALSDVTISTCHVSAKVGTRLVFDHDGKIIKKTPYPHPRGTTVSVKQLFSTLPVRHKEFQRNIKKKRACFPFAFCRDCQFLEGSPAMLPVQPAKLTVTGELRACRSWKTREGITEAVG","function_summary":"A nuclear DNA repair factor that assembles and regulates mismatch repair complexes in human cells. It uses an ATPase-driven scaffold to bind and organize repair partners on chromatin, stabilizing assemblies that correct replication errors and safeguard genome integrity. By maintaining high-fidelity repair in the nucleoplasm, it supports normal cell survival and suppresses oncogenic instability associated with tumor formation.","plain_language":"PMS2P2 has barely been studied. The model's best guess: A nuclear DNA repair factor that assembles and regulates mismatch repair complexes in human cells. It uses an ATPase-driven scaffold to bind and organize repair partners on chromatin, stabilizing assemblies that correct replication errors and safeguard genome integrity.","uniprot_summary":"Involved in DNA mismatch repair (MMR). Required for normal cell survival and tumor suppression.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0006298","label":"mismatch repair"}],"cellular_component":[{"id":"GO:0005654","label":"nucleoplasm"}]},"interpro":[{"id":"IPR036890","name":"Histidine kinase/HSP90-like ATPase superfamily","type":"homologous_superfamily","start":73,"end":274},{"id":"IPR038973","name":"DNA mismatch repair protein MutL/Mlh/Pms-like","type":"family","start":76,"end":245}],"reasoning":"I begin with the InterPro architecture. The core of the protein is defined by IPR036890 (Histidine kinase/HSP90-like ATPase superfamily, residues 73–274) and IPR038973 (DNA mismatch repair protein MutL/Mlh/Pms-like family, residues 76–245). The MutL/Pms-like family signature (IPR038973) sits squarely within the broader GHKL ATPase scaffold (IPR036890), an NTPase fold that drives clamp-like conformational switching in DNA repair assemblies. The ordered overlap—MutL-like family nested within a GHKL ATPase superfamily—establishes a Pms2-class MutL homolog: an ATPase-regulated adaptor that forms and remodels repair complexes rather than acting as a standalone enzyme. This architecture causes multivalent protein–protein interactions that assemble and stabilize mismatch repair machinery, directly supporting GO:0005515 protein binding as the operative molecular function.\n\nFrom this GHKL/MutL core, the mechanistic role follows. MutL-family modules coordinate DNA mismatch repair by coupling ATP-driven conformational states to recruitment and handoff steps. In human cells, this logic is used to resolve replication errors and small insertion/deletion loops. The MutL-like module here therefore drives the pathway formalized as GO:0006298 mismatch repair. The absence of catalytic nuclease or glycosylase motifs and the presence of an ATPase scaffold argue that the protein functions as a regulatory hub that binds partners and gates their assembly on chromatin.\n\nCellular placement is dictated by where mismatch repair operates. DNA replication and repair occur in the nuclear interior, and soluble assemblies form in the chromatin-rich interior rather than at membranes. The soluble GHKL scaffold and MutL family identity therefore place the complex in the nuclear interior, consistent with GO:0005654 nucleoplasm and the broader nuclear localization.\n\nThis mechanistic picture explains how the protein contributes to cell survival and tumor suppression. By ensuring efficient and accurate mismatch repair in the nucleoplasm, it prevents accumulation of replication-associated lesions and secondary genomic instability that foster oncogenic pathways. The MutL-like ATPase switch likely times the assembly of downstream effectors—endonucleases, exonucleases, and replication factors—so that repair proceeds with high fidelity.\n\nA concise mechanistic hypothesis emerges: the GHKL ATPase core cycles between open and closed states to clamp onto DNA-bound mismatch-recognition platforms, using ATP to stabilize assemblies and coordinate partner exchange. It likely binds mismatch sensors and replication/repair effectors to orchestrate strand scission, excision, and resynthesis. In human cells, this hub plausibly engages MutSα (MSH2–MSH6) or MutSβ (MSH2–MSH3), recruits MLH1 as a partner in MutL assemblies, and transiently couples to PCNA-loaded chromatin, EXO1, RPA, and DNA polymerase δ. These interactions collectively anchor the complex within the nucleoplasm and enforce high-fidelity mismatch repair that underpins normal cell viability and tumor suppression.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-O95744.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/O95744"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/O95744/entry","atlas":"/p/O95744"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}