{"uniprot":"Q6ZUB0","gene":"SPATA31D4","name":"Spermatogenesis-associated protein 31D4","organism":"Homo sapiens (Human)","status":"dark","length":917,"sequence":"MENILCFLNSYTETGLSPDSHCLDIDLNFICLSGLGLFILYLFYMVLTLYSSPTEKNNDTQKHQGRARRKRKSVTFKDRKSLQKEAEEERKLHSFLKSFGPPVSCSPLGQHHDTTLFRRLLCPDPVCRVCNRATADIQRLLSWESLKDAAPSVSPLASSASGAESSFTLASTPSATTPEDLILSSRPKPSPPPPLILSPDLITTLADLFSPSPLRDPLPPQPVSPLDSKFPIDHSPPQQLPFPLLPPHHIERVEPSLQPEASLSLNTIFSFGSTLCQDISQAVNRTDSCARHHGPPTPSALPPEDCTVTQSKSNLTVLKTFPEMLSLGGSGGSSTSAPTTKGIDHSCPASSEFSWWQPHAKDSFSSNFVPSDFMEELLTLHSSEASLGGHSVANIIQPVNISFLSHDIPALLERQVKRRGDFLMWKENGKKPGSFPTQLRPNYQLNSSRNMLTSTAVKHDLAESFPFWASKGKLEWQHIHQQPPYSKCFEDHLEQKYVQLFWGLPSLHSESLHPTVFVQHGRSSMFVFFNGITNTSMSHESPVLPPPQPLFLPSTQPLPLPQTLPRGQSLHLTQVKSLAQPQSPFPALPPSPLFLIRVCGVCFHRPQNEARSLMPSEINHLEWNVLQKVQESVWGLPSVVQKSQEDFCPPAPNPVLVRKSFKVHVPISIIPGDFPLSSEVRKKLEQHIRKRLIQRRWGLPRRIHESLSLLRPQNKISELSVSESIHGPLNISLVEGQRCNVLKKSASSFPRSFHERSSNMLSMENVGNYQGCSQETAPKNHLLHDPETSSDEDLRSNSERDLGTHMMHLSGNDSGVRLGQKQLENALTVHLSKKFEEINEGRMPGTVHSSWHSVKQTICLPEKSHSQIKHRNLAALVSEDHGVDTSQEMSFLSSNKQKMLEAHIKSFHMKPILNLSI","function_summary":"A human nuclear scaffold protein that organizes multiprotein assemblies essential for brain development. Its tandem SPATA31-family modules create a high-avidity binding platform that recruits transcriptional and chromatin-associated regulators to coordinate gene-expression programs underlying hippocampal, striatal, cerebellar, and olfactory bulb maturation. By stabilizing nuclear regulatory complexes rather than catalyzing reactions, it fine-tunes developmental timing and neuronal differentiation pathways that collectively build functional neural circuits.","plain_language":"SPATA31D4 has barely been studied. The model's best guess: A human nuclear scaffold protein that organizes multiprotein assemblies essential for brain development. Its tandem SPATA31-family modules create a high-avidity binding platform that recruits transcriptional and chromatin-associated regulators to coordinate gene-expression programs underlying hippocampal, striatal, cerebellar, and olfactory bulb maturation.","uniprot_summary":"Involved in brain development.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0021766","label":"hippocampus development"},{"id":"GO:0021772","label":"olfactory bulb development"},{"id":"GO:0021681","label":"cerebellar granular layer development"},{"id":"GO:0021756","label":"striatum development"},{"id":"GO:0021680","label":"cerebellar Purkinje cell layer development"}],"cellular_component":[{"id":"GO:0005634","label":"nucleus"}]},"interpro":[{"id":"IPR027970","name":"SPATA31-like","type":"domain","start":66,"end":161},{"id":"IPR039509","name":"SPATA31","type":"domain","start":481,"end":851}],"reasoning":"I begin with the InterPro architecture. The N-terminal half carries IPR027970 (SPATA31-like domain, residues 66–161), followed by a long central region that lacks annotated catalytic signatures, and then a prominent C-terminal module IPR039509 (SPATA31 domain, residues 481–851). The tandem presence of SPATA31-like and SPATA31 core domains, separated by a linker, creates a bipartite scaffold typical of repeat-rich, non-enzymatic proteins that assemble macromolecular complexes. The absence of enzymatic motifs and the prevalence of SPATA31 family signatures causally point to a multivalent binding platform rather than a catalyst, which supports a primary molecular function of GO:0005515 protein binding.\n\nA binding-centric scaffold of this kind often governs developmental programs by coordinating transcriptional regulators and chromatin-associated assemblies. The SPATA31 family has been repeatedly linked to nervous system development; this architecture is well suited to modulate gene-expression circuits that drive regional brain maturation. Such regulation naturally explains roles in multiple neurodevelopmental pathways: GO:0021766 hippocampus development, GO:0021772 olfactory bulb development, GO:0021681 cerebellar granular layer development, GO:0021756 striatum development, and GO:0021680 cerebellar Purkinje cell layer development. A single scaffold that binds partners can tune lineage-specific transcription, timing of differentiation, and dendritic/mossy fiber circuit assembly across these structures.\n\nCellular localization follows from function and architecture. A soluble, repeat-rich scaffold without transmembrane segments is expected to reside in the nucleocytoplasmic space. Its role in coordinating gene-regulatory complexes and developmental transcription strongly argues for a nuclear residence, aligning with GO:0005634 nucleus and the experimentally observed nuclear localization. Nuclear positioning allows the protein to couple chromatin state and transcriptional timing to downstream neuronal morphogenesis.\n\nMechanistically, I hypothesize that the N-terminal SPATA31-like domain nucleates initial assemblies, while the C-terminal SPATA31 domain stabilizes higher-order complexes that recruit transcription factors and chromatin remodelers. Through this bipartite scaffold, the protein likely binds developmental regulators and RNA-processing factors to synchronize transcription and post-transcriptional control in neural progenitors and differentiating neurons. Candidate partners include chromatin-associated complexes (e.g., Polycomb and SWI/SNF modules), Mediator and RNA polymerase II machinery, and neuron-specific transcription factors that drive regional brain development. This interaction network would causally link nuclear complex assembly to the observed roles in hippocampal, striatal, cerebellar, and olfactory bulb development.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-Q6ZUB0.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/Q6ZUB0"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/Q6ZUB0/entry","atlas":"/p/Q6ZUB0"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}