{"uniprot":"P04001","gene":"OPN1MW","name":"Medium-wave-sensitive opsin 1","organism":"Homo sapiens (Human)","status":"dark","length":364,"sequence":"MAQQWSLQRLAGRHPQDSYEDSTQSSIFTYTNSNSTRGPFEGPNYHIAPRWVYHLTSVWMIFVVIASVFTNGLVLAATMKFKKLRHPLNWILVNLAVADLAETVIASTISVVNQVYGYFVLGHPMCVLEGYTVSLCGITGLWSLAIISWERWMVVCKPFGNVRFDAKLAIVGIAFSWIWAAVWTAPPIFGWSRYWPHGLKTSCGPDVFSGSSYPGVQSYMIVLMVTCCITPLSIIVLCYLQVWLAIRAVAKQQKESESTQKAEKEVTRMVVVMVLAFCFCWGPYAFFACFAAANPGYPFHPLMAALPAFFAKSATIYNPVIYVFMNRQFRNCILQLFGKKVDDGSELSSASKTEVSSVSSVSPA","function_summary":"A cone opsin-class G protein–coupled receptor that binds retinal and converts photon absorption into downstream signaling at photoreceptor membranes. Its seven-helix bundle and retinal-binding pocket create a light-gated switch that activates heterotrimeric G proteins and arrestin pathways, thereby driving visual perception. The receptor resides predominantly in photoreceptor disc membranes and traffics through plasma-membrane–associated assemblies. Homomerization and assembly with signaling partners tune signal gain and duration, coupling light detection to broader GPCR-mediated pathways that can secondarily influence cell-division machinery.","plain_language":"OPN1MW has barely been studied. The model's best guess: A cone opsin-class G protein–coupled receptor that binds retinal and converts photon absorption into downstream signaling at photoreceptor membranes. Its seven-helix bundle and retinal-binding pocket create a light-gated switch that activates heterotrimeric G proteins and arrestin pathways, thereby driving visual perception.","uniprot_summary":"Visual pigments are the light-absorbing molecules that mediate vision. They consist of an apoprotein, opsin, covalently linked to cis-retinal.","go_terms":{"molecular_function":[{"id":"GO:0009881","label":"photoreceptor activity"},{"id":"GO:0042802","label":"identical protein binding"}],"biological_process":[{"id":"GO:0007186","label":"G protein-coupled receptor signaling pathway"},{"id":"GO:0032467","label":"positive regulation of cytokinesis"},{"id":"GO:0007601","label":"visual perception"}],"cellular_component":[{"id":"GO:0097381","label":"photoreceptor disc membrane"},{"id":"GO:0005886","label":"plasma membrane"}]},"interpro":[{"id":"IPR017452","name":"GPCR, rhodopsin-like, 7TM","type":"domain","start":70,"end":322},{"id":"IPR000378","name":"Opsin red/green sensitive","type":"family","start":20,"end":37},{"id":"IPR050125","name":"G-protein coupled receptor opsins","type":"family","start":53,"end":339},{"id":"IPR000276","name":"G protein-coupled receptor, rhodopsin-like","type":"family","start":55,"end":337},{"id":"IPR001760","name":"Opsin","type":"family","start":76,"end":88},{"id":"IPR000378","name":"Opsin red/green sensitive","type":"family","start":100,"end":115},{"id":"IPR000378","name":"Opsin red/green sensitive","type":"family","start":162,"end":176},{"id":"IPR001760","name":"Opsin","type":"family","start":190,"end":202},{"id":"IPR000378","name":"Opsin red/green sensitive","type":"family","start":206,"end":220},{"id":"IPR000378","name":"Opsin red/green sensitive","type":"family","start":287,"end":302},{"id":"IPR001760","name":"Opsin","type":"family","start":301,"end":313},{"id":"IPR000378","name":"Opsin red/green sensitive","type":"family","start":332,"end":344},{"id":"IPR027430","name":"Visual pigments (opsins) retinal binding site","type":"binding_site","start":306,"end":322}],"reasoning":"I begin with the InterPro architecture. The core transmembrane engine is IPR017452 (GPCR, rhodopsin-like, 7TM domain, residues 70–322), which establishes a seven-helix bundle that transduces extracellular signals via intracellular G-protein coupling. This scaffold is reinforced by multiple opsin-family signatures that specialize the rhodopsin-like GPCR fold for light sensing: IPR050125 (G-protein coupled receptor opsins family, residues 53–339) and IPR000276 (G protein-coupled receptor, rhodopsin-like family, residues 55–337) define the canonical class A GPCR topology and coupling logic. Within this framework, several opsin-specific family marks cluster across the N- to mid-region: IPR000378 (Opsin red/green sensitive family, residues 20–37), IPR000378 (Opsin red/green sensitive family, residues 100–115), IPR000378 (Opsin red/green sensitive family, residues 162–176), IPR000378 (Opsin red/green sensitive family, residues 206–220), and IPR000378 (Opsin red/green sensitive family, residues 287–302). These collectively specify the Müllerian aldehyde/retinal-based chromophore system and the spectral-tuning residues typical of cone opsins. Two additional opsin-family signatures, IPR001760 (Opsin family, residues 76–88) and IPR001760 (Opsin family, residues 190–202), plus IPR001760 (Opsin family, residues 301–313), and IPR000378 (Opsin red/green sensitive family, residues 332–344), reinforce that the entire polypeptide is an opsin-class receptor. Crucially, IPR027430 (Visual pigments retinal binding site, residues 306–322) pinpoints the retinal Schiff-base pocket in the seventh helix that forms the light-activated chromophore. The ordered layout—N-terminal opsin-family determinants feeding into a central 7TM rhodopsin-like core and culminating in a defined retinal-binding site—causally dictates a light-gated GPCR.\n\nThis architecture drives the molecular function. The rhodopsin-like 7TM bundle coupled to a covalently bound retinal cofactor creates a bistable photosensor that switches between ground and active states upon photon absorption; this is the essence of GO:0009881 photoreceptor activity. The presence of multiple opsin-family motifs and the conserved GPCR coupling surfaces implies assembly with heterotrimeric G proteins and arrestins; such assemblies commonly require homo-oligomerization or paralog pairing, supporting GO:0042802 identical protein binding through receptor–receptor or receptor–receptor complex formation that tunes signaling gain.\n\nFrom function to process, light-triggered receptor activation initiates a canonical GPCR cascade. The opsin fold and retinal chemistry compel engagement of the cone transducin pathway and arrestin-mediated feedback, placing the protein squarely in GO:0007186 G protein-coupled receptor signaling pathway. Photon capture and downstream signaling underlie GO:0007601 visual perception by converting luminance information into electrical signals. Cone-driven signaling can secondarily modulate cell-cycle machinery through G-protein and kinase networks; thus, sustained or misregulated signaling can elevate cytokinetic machinery activity, aligning with GO:0032467 positive regulation of cytokinesis as a downstream, context-dependent outcome of receptor-driven pathways.\n\nCellular location follows directly from the membrane-embedded 7TM core and the photoreceptor specialization. The multi-pass topology and opsin identity place the receptor in specialized membranes of photoreceptors. The retinal-binding pocket and cone opsin signatures align with accumulation in the photoreceptor outer segment, specifically the GO:0097381 photoreceptor disc membrane where discs concentrate visual pigments. Trafficking and signaling interfaces rationalize presence at the GO:0005886 plasma membrane, which serves as a staging site for receptor maturation and signaling complex assembly.\n\nMechanistically, the protein binds 11-cis-retinal within the IPR027430-defined pocket; photon absorption isomerizes the chromophore, reshaping the 7TM bundle to expose G-protein coupling surfaces. This triggers cone transducin activation and recruits arrestins, with receptor homomerization fine-tuning signal amplitude. I therefore hypothesize interactions with cone transducin (GNAT2) and arrestins (ARRB2), plus scaffolds that organize disc membranes and trafficking hubs. These assemblies localize the receptor to photoreceptor disc and plasma membranes, where light-gated GPCR signaling drives visual perception and, under certain regimes, can modulate cytokinetic pathways.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-P04001.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/P04001"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/P04001/entry","atlas":"/p/P04001"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}