{"uniprot":"O95473","gene":"SYNGR4","name":"Synaptogyrin-4","organism":"Homo sapiens (Human)","status":"dark","length":234,"sequence":"MHIPKSLQELANSEAVQFLRRPKTITRVFEGVFSLIVFSSLLTDGYQNKMESPQLHCILNSNSVACSFAVGAGFLAFLSCLAFLVLDTQETRIAGTRFKTAFQLLDFILAVLWAVVWFMGFCFLANQWQHSPPKEFLLGSSSAQAAIAFTFFSILVWIFQAYLAFQDLRNDAPVPYKRFLDEGGMVLTTLPLPSANSPVNMPTTGPNSLSYASSALSPCLTAPKSPRLAMMPDN","function_summary":"A neuronal vesicle-associated tetraspan that assembles and stabilizes synaptic vesicle membranes through a Marvel-type multi-pass core. By scaffolding vesicle-resident proteins and lipid microdomains, it organizes vesicle biogenesis and recycling pathways that underpin regulated exocytosis. Its membrane-embedded architecture positions it on synaptic vesicles, where it coordinates trafficking modules that shape synaptic vesicle dynamics and contribute to maturation of midbrain dopaminergic pathways.","plain_language":"SYNGR4 has barely been studied. The model's best guess: A neuronal vesicle-associated tetraspan that assembles and stabilizes synaptic vesicle membranes through a Marvel-type multi-pass core. By scaffolding vesicle-resident proteins and lipid microdomains, it organizes vesicle biogenesis and recycling pathways that underpin regulated exocytosis.","uniprot_summary":"Involved in synaptic vesicle function.","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0021762","label":"substantia nigra development"}],"cellular_component":[{"id":"GO:0008021","label":"synaptic vesicle"}]},"interpro":[{"id":"IPR008253","name":"Marvel domain","type":"domain","start":18,"end":169},{"id":"IPR016579","name":"Synaptogyrin","type":"family","start":6,"end":233}],"reasoning":"I begin with the InterPro architecture. The polypeptide carries IPR008253 (Marvel domain, residues 18–169), a four-helix transmembrane module characteristic of vesicular membrane organizers that cluster cholesterol-rich microdomains and scaffold membrane curvature. This core is embedded within IPR016579 (Synaptogyrin family, residues 6–233), which defines a neuronal vesicle-associated tetraspanin-like family specialized for synaptic vesicle biology. The ordered layout—an N-terminal cytosolic segment, a central Marvel tetraspan core, and short luminal loops—creates a multi-pass membrane architecture that nucleates vesicle-associated protein assemblies rather than catalyzing reactions. Such scaffolding architecture causally supports GO:0005515 protein binding as the primary molecular function, with multivalent cytosolic and luminal surfaces mediating selective interactions.\n\nFrom this scaffold, the biological role follows. Synaptogyrin-family Marvel modules concentrate and stabilize synaptic vesicle membranes, shaping vesicle biogenesis, recycling, and cargo sorting. By organizing vesicle-associated complexes, this architecture drives neuronal circuit maturation; in dopaminergic midbrain pathways, that organizing role scales up to developmental outcomes formalized as GO:0021762 substantia nigra development.\n\nThe cellular context is dictated by the membrane-embedded Marvel core and the synaptogyrin family signature. A multi-pass topology and vesicle-scaffold function place the protein at the synaptic vesicle membrane, consistent with a multi-pass membrane protein that resides on GO:0008021 synaptic vesicles. The experimentally observed membrane residency and tetraspan layout reinforce this vesicular localization.\n\nMechanistically, the Marvel domain forms a curvature-stabilizing tetraspan that clusters synaptic vesicle proteins and lipids, while cytosolic termini recruit trafficking machinery. This causes selective assembly of exo/endocytic modules that tune neurotransmitter loading and release. I hypothesize that the protein binds and organizes core synaptic vesicle partners—synaptobrevin/VAMP, synaptotagmin, and adaptor complexes—thereby coupling vesicle identity to regulated exocytosis and recycling. In neurons, this vesicle-organizing mechanism provides the platform that influences synaptic vesicle dynamics and ultimately contributes to maturation of substantia nigra circuitry.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-O95473.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/O95473"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/O95473/entry","atlas":"/p/O95473"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}