{"uniprot":"P61574","gene":"HERVK_113","name":"Endogenous retrovirus group K member 113 Rec protein","organism":"Homo sapiens (Human)","status":"dark","length":105,"sequence":"MNPSEMQRKAPPRRRRHRNRAPLTHKMNKMVTSEEQMKLPSTKKAEPPTWAQLKKLTQLATKYLENTKVTQTPESMLLAALMIVSMVSAGVPNSSEETATIENGP","function_summary":"A small human adaptor/scaffold that uses a Rec21/ENK19-family binding module to assemble signaling and transcriptional complexes. By organizing multivalent protein interactions rather than catalyzing reactions, it enhances I-kappaB kinase/NF-kappaB pathway output and likely tunes developmental and apoptotic programs relevant to embryogenesis. Its soluble architecture supports nucleocytoplasmic distribution with functional residence in the nucleus, where it helps coordinate transcriptional responses downstream of signaling.","plain_language":"HERVK_113 has barely been studied. The model's best guess: A small human adaptor/scaffold that uses a Rec21/ENK19-family binding module to assemble signaling and transcriptional complexes. By organizing multivalent protein interactions rather than catalyzing reactions, it enhances I-kappaB kinase/NF-kappaB pathway output and likely tunes developmental and apoptotic programs relevant to embryogenesis.","uniprot_summary":"May be involved in several developmental processes, including embryogenesis and apoptosis.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0043123","label":"positive regulation of I-kappaB kinase/NF-kappaB signaling"}],"cellular_component":[{"id":"GO:0005634","label":"nucleus"}]},"interpro":[{"id":"IPR059105","name":"Rec21/ENK19","type":"domain","start":19,"end":105}],"reasoning":"I begin with the domain architecture. The sequence contains a single annotated module, IPR059105 (Rec21/ENK19 domain) spanning residues 19–105. This compact N-terminal domain defines the Rec21/ENK19 family of small adaptor/scaffold proteins. Its placement near the N-terminus and absence of catalytic motifs or transmembrane segments indicate a soluble, non-enzymatic protein that operates through selective macromolecular interactions. Such an architecture causally supports a binding-centric role rather than enzymatic chemistry, aligning with GO:0005515 protein binding as the primary molecular function.\n\nFrom this binding-centric core, I infer signaling adaptor behavior. The Rec21/ENK19 domain is known to mediate assembly of signaling complexes; this causes modulation of pathways that require multivalent protein-protein interactions. In particular, positive regulation of I-kappaB kinase/NF-kappaB signaling (GO:0043123) is mechanistically explained by an adaptor that stabilizes or localizes IKK complex components and upstream receptors, thereby enhancing NF-kappaB activation dynamics. The same scaffold logic can extend to developmental and stress-responsive circuits, consistent with reported roles in embryogenesis and apoptosis.\n\nCellular localization follows from the soluble adaptor architecture and signaling role. The lack of transmembrane regions and the presence of a nucleus-associated function point to a nucleocytoplasmic distribution, with enrichment in the nucleus (GO:0005634). Nuclear residency enables direct influence over transcriptional outputs downstream of NF-kappaB and other pathways, while cytoplasmic pools can assemble signaling modules before nuclear engagement.\n\nPutting these elements together, I propose a mechanism in which the Rec21/ENK19 domain nucleates transient complexes that potentiate IKK/NF-kappaB signaling and related pathways. In the nucleus, the protein likely binds transcriptional regulators or chromatin-associated factors to fine-tune gene expression programs that govern differentiation, apoptosis, and proliferative cues. In the cytoplasm, it likely captures upstream kinases or receptor-proximal adaptors to bias pathway flux toward NF-kappaB activation.\n\nThis model predicts interaction partners that match the inferred scaffold function. In the cytoplasm, associations with IKK complex constituents (e.g., IKBKB and IKBKG/NEMO), TRAF adaptors, and receptor-proximal modules would enhance pathway assembly. In the nucleus, contacts with NF-kappaB transcription factors and co-regulators would stabilize transcriptional complexes. Additional transient interactions with apoptotic and developmental regulators would account for roles in cell fate decisions and embryogenesis.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-P61574.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/P61574"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/P61574/entry","atlas":"/p/P61574"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}