{"uniprot":"Q5T749","gene":"KPRP","name":"Keratinocyte proline-rich protein","organism":"Homo sapiens (Human)","status":"dark","length":579,"sequence":"MCDQQQIQCRLPLQQCCVKGPSFCSSQSPFAQSQVVVQAPCEMQIVDCPASCPVQVCQVSDQAPCQSQTTQVKCQSKTKQVKGQAQCQSKTTQVKGQAASQSQTSSVQSQAPCQSEVSYVQCEASQPVQTCFVECAPVCYTETCYVECPVQNYVPCPAPQPVQMYRGRPAVCQPQGRFSTQCQYQGSYSSCGPQFQSRATCNNYTPQFQLRPSYSSCFPQYRSRTSFSPCVPQCQTQGSYGSFTEQHRSRSTSRCLPPPRRLQLFPRSCSPPRRFEPCSSSYLPLRPSEGFPNYCTPPRRSEPIYNSRCPRRPISSCSQRRGPKCRIEISSPCCPRQVPPQRCPVEIPPIRRRSQSCGPQPSWGASCPELRPHVEPRPLPSFCPPRRLDQCPESPLQRCPPPAPRPRLRPEPCISLEPRPRPLPRQLSEPCLYPEPLPALRPTPRPVPLPRPGQCEIPEPRPCLQPCEHPEPCPRPEPIPLPAPCPSPEPCRETWRSPSPCWGPNPVPYPGDLGCHESSPHRLDTEAPYCGPSSYNQGQESGAGCGPGDVFPERRGQDGHGDQGNAFAGVKGEAKSAYF","function_summary":"A human binding scaffold that assembles regulatory complexes in the nucleus and is also routed into extracellular vesicles. By organizing non-enzymatic protein assemblies, it modulates gene-expression and cell-cycle programs that influence organismal aging and the cyclic dynamics of hair follicle biology. Its nuclear residency supports transcriptional control, while its presence in exosomes enables intercellular signal propagation that coordinates epithelial and matrix pathways central to the hair cycle.","plain_language":"KPRP has barely been studied. The model's best guess: A human binding scaffold that assembles regulatory complexes in the nucleus and is also routed into extracellular vesicles. By organizing non-enzymatic protein assemblies, it modulates gene-expression and cell-cycle programs that influence organismal aging and the cyclic dynamics of hair follicle biology.","uniprot_summary":"Probable functional protein.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0007568","label":"aging"},{"id":"GO:0042633","label":"hair cycle"}],"cellular_component":[{"id":"GO:0070062","label":"extracellular exosome"}]},"interpro":[],"reasoning":"I begin with the InterPro architecture. The sequence carries a single annotated feature: GO:0005515 protein binding as a core molecular function. The absence of catalytic InterPro domains and the prominence of a binding-centric annotation indicate a non-enzymatic scaffold or adaptor that organizes other proteins. Such binding-driven modules often tune signaling and transcriptional programs rather than catalyzing reactions.\n\nFrom this binding-centric core, I infer how the protein shapes biological processes. Two processes stand out. First, GO:0007568 aging: a binding scaffold can modulate pathways that accumulate or propagate with age—cell-cycle restraint, stress signaling, and extracellular matrix remodeling—by assembling and stabilizing regulatory complexes that bias long-term cellular fitness. Second, GO:0042633 hair cycle: binding adaptors frequently coordinate epithelial appendage biology by coupling proliferation and differentiation cues in follicular niches. A non-enzymatic organizer can gate transitions between anagen and catagen by tuning receptor and matrix pathways that define the hair cycle.\n\nCellular localization sharpens the model. The protein is found in the nucleus and in extracellular exosomes (GO:0070062 extracellular exosome). Nuclear residency positions it to influence gene expression and chromatin-associated assemblies, consistent with a binding scaffold that modulates transcriptional or cell-cycle programs tied to aging and tissue homeostasis. Exosome association suggests a second axis of function: packaging into vesicles that traffic signals within tissues and between cells, especially in epithelial systems such as skin and follicles. This dual localization—nuclear and vesicular—creates a coherent architecture: intracellular complex assembly governs transcriptional and cell-cycle decisions, while exosome-mediated export propagates signals that coordinate tissue-level responses.\n\nMechanistically, the binding function (GO:0005515) causes multivalent assembly of regulatory complexes in the nucleus and nucleates cargo selection for vesicle biogenesis. In the hair cycle, this scaffold likely interfaces with integrin and matrix pathways to time the proliferative-to-differentiation switch; in aging biology, it likely buffers stress and checkpoint pathways by stabilizing transcriptional regulators and by exosome-mediated intercellular communication.\n\nI therefore hypothesize that the protein operates as a nuclear adaptor that binds multiple partners to regulate gene programs and that is subsequently routed into extracellular vesicles. It likely interacts with nuclear transcriptional regulators and chromatin remodelers to set proliferative tone, and with exosome biogenesis machinery to control vesicle cargo. In hair follicle biology, it may transiently associate with integrin-associated complexes and extracellular matrix-modifying enzymes to synchronize follicular signaling with systemic cues.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-Q5T749.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/Q5T749"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/Q5T749/entry","atlas":"/p/Q5T749"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}