{"uniprot":"Q96KJ4","gene":"MSLNL","name":"Mesothelin-like protein","organism":"Homo sapiens (Human)","status":"dark","length":702,"sequence":"MAAAVTIPGPRIGALQSSGLTLLLSLAAHCSGPQAKVLSPGGLDASGANLWASANCSLLQGFWCQPASQLPRDQLSALIQRLALLQVPLQAWQLSCLANLASRCGLQDDFTLHPPNLLLFYNLSQVREADCRAFIRRAAQGDVELLSHLPDQRVALWRAAVACLVGAGLRLSASDQQLLGALVCDMDASSIGAADPHMLENLRRCPRLTAAQRIALNSLLAGGKTSLGPPGSWTLEGLQALGPLATYISPHLWAQVQEAVGLGFFRSVVASCQVGRLGQREARCFVTSFLESKTKPVSSRPRLSTGNITAATLRDDLFLVHYDCAELESCLDGCILRTNLDTLLQHLLPTECQHVVKAKLAQIYPQGLPEDQLRLITSLVYLYSRTEIGQWSITSQDTVMALLASDVALENQTEAVLQKFLEHNGTVSGALLLAIGGTRLCWMSPHQIQTIHPQELRLAGALDLSSCPQSRKDVLYTKAHETFGSSGTLAAYYRLMRPYLGGSPGGAQPPSPVPPGGAPVEELRHLAHANISMDIDTFTSLNPLELQSLDVGNVTALLGHNVGDLQKARSHPTVRAWLRSLNSSTLGQLGLDASPTSPTGPAHGTRGPPSTTHQVLHLVHTSGLPTNDAQASTSGSLWAPLGYLPLAMALPCSLLCLLHWGTCILVSVDSVASGWLGSQGSGAGKTEVLDSAGRPLGLTGQL","function_summary":"A human extracellularly oriented binding scaffold that assembles and stabilizes protein complexes at the cell surface. Its architecture favors multivalent interactions rather than catalysis, positioning it to organize adhesion and matrix-proximal assemblies that tune mechanosensory systems. By scaffolding partners at the plasma membrane, it likely contributes to the assembly and maintenance of auditory apparatus and broader mechanotransduction pathways.","plain_language":"MSLNL has barely been studied. The model's best guess: A human extracellularly oriented binding scaffold that assembles and stabilizes protein complexes at the cell surface. Its architecture favors multivalent interactions rather than catalysis, positioning it to organize adhesion and matrix-proximal assemblies that tune mechanosensory systems.","uniprot_summary":"May play a role in auditory apparatus.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0007605","label":"sensory perception of sound"}],"cellular_component":[{"id":"GO:0005886","label":"plasma membrane"}]},"interpro":[{"id":"IPR026664","name":"Stereocilin-related","type":"family","start":34,"end":608},{"id":"IPR010335","name":"Mesothelin","type":"family","start":49,"end":595}],"reasoning":"I begin with the InterPro architecture. The sequence carries IPR026664 (Stereocilin-related family) spanning residues 34–608 and IPR010335 (Mesothelin family) spanning residues 49–595. The broad overlap of these two family signatures across nearly the entire ectodomain indicates a large, secreted/lumenal module that lacks obvious catalytic cores but is specialized for extracellular interactions. The mesothelin-related family is classically associated with secreted or membrane-tethered glycoproteins that mediate adhesion and matrix/protein binding, while the stereocilin-related family points to extracellular binding modules implicated in mechanosensory systems. The absence of intracellular enzymatic motifs and the dominance of extracellular-binding architectures causally point to a non-enzymatic, adhesive scaffold whose primary chemistry is multivalent protein binding.\n\nFrom this architecture, the molecular function resolves to GO:0005515 protein binding. The tandem extracellular family signatures predict a high-affinity, multivalent binding surface that organizes complexes rather than catalyzing reactions. Such modules typically stabilize and position other extracellular or membrane-associated proteins.\n\nThis binding-driven mechanism naturally feeds into the biological process of mechanosensation. The stereocilin-related signature is emblematic of hair-cell and mechanotransduction contexts, and the mesothelin/stereocilin-like fold provides a structural solution for assembling and stabilizing extracellular complexes that tune stimulus capture and signal initiation. This causal chain—extracellular binding scaffold leading to assembly and tuning of mechanosensory apparatus—maps to GO:0007605 sensory perception of sound.\n\nCellular placement follows from the same logic. A large extracellular module that organizes adhesion and signaling complexes is most effective at the cell surface. The architecture and functional inference therefore place the protein at the GO:0005886 plasma membrane, where it can bridge extracellular cues to membrane-proximal assemblies.\n\nMechanistically, I hypothesize that the protein is synthesized with a signal peptide and secreted or delivered to the cell surface, where it forms a pericellular scaffold that binds other extracellular and membrane proteins. By clustering adhesion molecules and extracellular matrix components adjacent to the plasma membrane, it likely stabilizes the local microenvironment of mechanotransduction complexes and modulates their accessibility and coupling to intracellular signaling. Candidate partners include stereocilia-associated adhesion systems and membrane-proximal extracellular modules; through these interactions, the protein would fine-tune the assembly and maintenance of the auditory apparatus.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-Q96KJ4.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/Q96KJ4"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/Q96KJ4/entry","atlas":"/p/Q96KJ4"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}