{"uniprot":"Q9NU23","gene":"LYRM2","name":"LYR motif-containing protein 2","organism":"Homo sapiens (Human)","status":"dark","length":88,"sequence":"MAASRLPPATLTLKQFVRRQQVLLLYRRILQTIRQVPNDSDRKYLKDWAREEFRRNKSATEEDTIRMMITQGNMQLKELEKTLALAKS","function_summary":"A soluble mitochondrial assembly factor that uses a LYR-module scaffold to bind and stabilize early intermediates of the NADH:ubiquinone oxidoreductase. By organizing protein–protein interfaces rather than catalyzing reactions, it promotes orderly biogenesis of the respiratory chain’s entry complex at the inner-membrane interface, thereby supporting efficient maturation and stability of the assembled enzyme within mitochondria.","plain_language":"LYRM2 has barely been studied. The model's best guess: A soluble mitochondrial assembly factor that uses a LYR-module scaffold to bind and stabilize early intermediates of the NADH:ubiquinone oxidoreductase. By organizing protein–protein interfaces rather than catalyzing reactions, it promotes orderly biogenesis of the respiratory chain’s entry complex at the inner-membrane interface, thereby supporting efficient maturation and stability of the assembled enzyme within mitochondria.","uniprot_summary":"Involved in the assembly of mitochondrial NADH:ubiquinone oxidoreductase complex (complex I).","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0032981","label":"mitochondrial respiratory chain complex I assembly"}],"cellular_component":[{"id":"GO:0005747","label":"mitochondrial respiratory chain complex I"}]},"interpro":[{"id":"IPR045293","name":"LYRM2, LYR domain","type":"domain","start":17,"end":79},{"id":"IPR008011","name":"Complex 1 LYR protein domain","type":"domain","start":20,"end":78}],"reasoning":"I begin with the InterPro architecture. The polypeptide carries IPR045293 (LYRM2, LYR domain, residues 17–79) and IPR008011 (Complex I LYR protein domain, residues 20–78). The two signatures overlap almost entirely, indicating a single LYR-type module that defines the protein’s biochemical and assembly roles. LYR domains are compact, soluble assembly factors that use an N-terminal LYR motif and adjacent helical elements to mediate avid protein–protein interactions rather than catalysis. This architecture causes a binding-centric molecular function: the LYR module forms a docking surface that stabilizes assembly intermediates and recruits partner proteins, consistent with GO:0005515 protein binding as the primary molecular function.\n\nFrom this binding-centric core, I infer the biological process. LYR-family proteins are canonically dedicated to mitochondrial respiratory chain complex I biogenesis. The explicit Complex I LYR domain (IPR008011) ties the LYR module to assembly steps of the NADH:ubiquinone oxidoreductase. Such a role naturally drives GO:0032981 mitochondrial respiratory chain complex I assembly. The causal chain is: the LYR domain confers high-affinity assembly contacts; these contacts nucleate and stabilize early complex I subassemblies; stabilization promotes maturation of the holoenzyme.\n\nCellular localization follows from where complex I is built and where LYR assembly factors operate. Complex I is built and resides at the mitochondrial inner membrane, with assembly modules straddling the matrix side and inner-membrane-proximal regions. The LYR architecture lacks transmembrane segments and therefore acts as a soluble assembly cofactor that associates with the inner-membrane-embedded complex. This places the protein functionally at GO:0005747 mitochondrial respiratory chain complex I and supports a mitochondrial localization.\n\nMechanistically, the LYR domain provides a scaffold that organizes early assembly modules and coordinates cofactor delivery. By binding nascent complex I subunits and assembly chaperones, it stabilizes intermediates and prevents premature dissociation. I hypothesize that it transiently associates with core and accessory complex I subunits (for example, NDUFS and NDUFV modules) and with matrix-exposed assembly factors that shepherd biogenesis. Through these interactions, it promotes orderly assembly at the inner membrane interface, ensuring efficient maturation of the respiratory chain’s entry complex.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-Q9NU23.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/Q9NU23"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/Q9NU23/entry","atlas":"/p/Q9NU23"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}