{"uniprot":"A8CG34","gene":"POM121C","name":"Nuclear envelope pore membrane protein POM 121C","organism":"Homo sapiens (Human)","status":"dark","length":1229,"sequence":"MSPAAAAAGAGERRRPIASVRDGRGRGCGGPAGAALLGLSLVGLLLYLVPAAAALAWLAVGTTAAWWGLSREPRGSRPLSSFVQKARHRRTLFASPPAKSTANGNLLEPRTLLEGPDPAELLLMGSYLGKPGPPQPAPAPEGQDLRNRPGRRPPARPAPRSTPPSQPTHRVHHFYPSLPTPLLRPSGRPSPRDRGTLPDRFVITPRRRYPIHQTQYSCPGVLPTVCWNGYHKKAVLSPRNSRMVCSPVTVRIAPPDRRFSRSAIPEQIISSTLSSPSSNAPDPCAKETVLSALKEKKKKRTVEEEDQIFLDGQENKRRRHDSSGSGHSAFEPLVASGVPASFVPKPGSLKRGLNSQSSDDHLNKRSRSSSMSSLTGAYTSGIPSSSRNAITSSYSSTRGISQLWKRNGPSSSPFSSPASSRSQTPERPAKKIREEELCHHSSSSTPLAADKESQGEKAADTTPRKKQNSNSQSTPGSSGQRKRKVQLLPSRRGEQLTLPPPPQLGYSITAEDLDLEKKASLQWFNQALEDKSDAASNSVTETPPTTQPSFTFTLPAAATASPPTSLLAPSTNPLLESLKKMQTPPSLPPCPESAGAATTEALSPPKTPSLLPPLGLSQSGPPGLLPSPSFDSKPPTTLLGLIPAPSMVPATDTKAPPTLQAETATKPQATSAPSPAPKQSFLFGTQNTSPSSPAAPAASSASPMFKPIFTAPPKSEKEGLTPPGPSVSATAPSSSSLPTTTSTTAPTFQPVFSSMGPPASVPLPAPFFKQTTTPATAPTTTAPLFTGLASATSAVAPITSASPSTDSASKPAFGFGINSVSSSSVSTTTSTATAASQPFLFGAPQASAASFTPAMGSIFQFGKPPALPTTTTVTTFSQSLPTAVPTATSSSAADFSGFGSTLATSAPATSSQPTLTFSNTSTPTFNIPFGSSAKSPLPSYPGANPQPAFGAAEGQPPGAAKPALTPSFGSSFTFGNSAAPAPATAPTPAPASTIKIVPAHVPTPIQPTFGGATHSAFGLKATASAFGAPASSQPAFGGSTAVFSFGAATSSGFGATTQTASSGSSSSVFGSTTPSPFTFGGSAAPAGSGSFGINVATPGSSATTGAFSFGAGQSGSTATSTPFTGGLGQNALGTTGQSTPFAFNVGSTTESKPVFGGTATPTFGQNTPAPGVGTSGSSLSFGASSAPAQGFVGVGPFGSAAPSFSIGAGSKTPGARQRLQARRQHTRKK","function_summary":"A large scaffold component of the nuclear pore that organizes the transport conduit between nucleus and cytoplasm. By forming multivalent assemblies that stabilize pore architecture and anchor transport-selective elements, it supports receptor-driven cargo translocation into the nucleus and maintains nuclear organization. Its soluble-facing networks and membrane-proximal lattice position it at the nuclear envelope with extensions into the nucleoplasm, where it coordinates selective nucleocytoplasmic exchange.","plain_language":"POM121C has barely been studied. The model's best guess: A large scaffold component of the nuclear pore that organizes the transport conduit between nucleus and cytoplasm. By forming multivalent assemblies that stabilize pore architecture and anchor transport-selective elements, it supports receptor-driven cargo translocation into the nucleus and maintains nuclear organization.","uniprot_summary":"Component of the nuclear pore complex (NPC), a complex structure suspended within the nuclear envelope and containing multiple copies of individual nucleoporins. The NPC mediates transport across the nuclear envelope.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0006606","label":"protein import into nucleus"},{"id":"GO:0006997","label":"nucleus organization"}],"cellular_component":[{"id":"GO:0005654","label":"nucleoplasm"},{"id":"GO:0031965","label":"nuclear membrane"}]},"interpro":[{"id":"IPR026054","name":"Nuclear pore complex protein","type":"family","start":1,"end":1218}],"reasoning":"I begin with the InterPro architecture: IPR026054 (Nuclear pore complex protein family) spans residues 1–1218, covering essentially the entire polypeptide. A full-length, single-family signature of this breadth is characteristic of nucleoporins that form the scaffold of the nuclear pore complex (NPC). Such nucleoporin-family architectures typically encode extended, low-complexity and repeat-rich regions that assemble into higher-order NPC lattices and rings. This architecture causes multivalent, avid interactions with other nucleoporins and transport receptors, establishing a primary molecular function of protein binding (GO:0005515).\n\nFrom this scaffolded binding capacity, the molecular function propagates to transport. NPC scaffold nucleoporins create the conduit and selective barrier that govern nuclear–cytoplasmic exchange. By stabilizing the central channel and anchoring FG-repeat nucleoporins, this protein supports karyopherin-mediated cargo translocation. That structural role directly drives protein import into the nucleus (GO:0006606) and sustains broader nucleus organization (GO:0006997), because the NPC is both a trafficking hub and an architectural centerpiece of the nuclear envelope.\n\nThe cellular context follows from the same architecture. Scaffold nucleoporins localize to the NPC embedded within the nuclear envelope, which places the protein at the nuclear membrane (GO:0031965) and within the nucleoplasm (GO:0005654) as part of the NPC’s soluble-facing networks. The experimentally observed subcellular location in the nucleus is consistent with this NPC-centric residency.\n\nMechanistically, the nucleoporin-family scaffold likely forms a ring-like or lattice element that positions FG-repeat channels and transport platforms. By concentrating and ordering these modules, it creates a selective permeability barrier and dynamic binding surface for import/export receptors. I hypothesize that it binds importin-α/β complexes and Ran GTPase cycles indirectly via associated FG-nucleoporins, thereby gating cargo flow. In this framework, probable interaction partners include central-bubble nucleoporins (for lattice assembly), FG-repeat nucleoporins (for transport selectivity), and the Ran/karyopherin machinery that executes directionality of nuclear import and export.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-A8CG34.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/A8CG34"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/A8CG34/entry","atlas":"/p/A8CG34"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}