{"uniprot":"Q6ZR37","gene":"PLEKHG7","name":"Pleckstrin homology domain-containing family G member 7","organism":"Homo sapiens (Human)","status":"dark","length":691,"sequence":"MEKTESFCPEVPPQDCGASPRPSLRSLPKNQGSLLQFDRQAPGRISTSPTLRRLRTRGCGTRQDAWQVTTWGSWGAPVGFPCYLSKSLPGSPKDSSHLLSPLRLHSRLTSEPERALNAADSLEPQTRPTDKYLPPELQPVNEGSLHQASLRQQEGHFLPSPTLRHPSPQGEELHPSRFYEHRRSSVVLNLPGLEVFPGDLLVSDGAADYLCHPLLLLNSESKKPRWPFSKRGVGKDKHKHISDLENCLSSVKITSFRGYDFYGLKDKTWDEVLETHHKLPTDQLDLKKQQEAVWELFTSECTYFLDHLLVLKMIFMNTLRYLQTHEYLLDVDLWRLFANLEELTQTSLGFVNSLFGIIKDYVDASEISSSLDFISVLTKYFRGSLCQSHQTYCLNYSAAIFYLESLRQRDDFGIYLKWCEQNEQCRRLHVPELLVAPLQRLTRYPLLLKNIWKRSMDSAEKIMIYSIKEKVEKSIRDLEGKVKWLDNFQKFRYLQEIIVWPPLWDRDKRFFIPECLKHIFKEHMAENILSPTSRHLLYEGKLTLAESTRFLDVYLFLFNDFLLVTKTKCNKKKLGGSDPGLMCPSLTPELQAVIKEGGSCTVLDQPIPLDRLVVKSIEPLHVSVFGLRNAFLIQHENRYRQCIAAFLLQAQTENIKKTWMAQITTAISCFTKSQETKKISLFTLPAESSEI","function_summary":"A cytosolic signaling enzyme that uses a DH–PH tandem to activate small GTPases and assemble multiprotein complexes. By catalyzing nucleotide exchange on membrane-proximal targets and docking via its PH module, it promotes pathways governed by Rac/Cdc42 and can potentiate IKK-dependent NF-kappaB signaling. Its soluble architecture supports a cytosolic pool with transient membrane engagement, coordinating small GTPase signaling with inflammatory and stress-responsive pathways.","plain_language":"PLEKHG7 has barely been studied. The model's best guess: A cytosolic signaling enzyme that uses a DH–PH tandem to activate small GTPases and assemble multiprotein complexes. By catalyzing nucleotide exchange on membrane-proximal targets and docking via its PH module, it promotes pathways governed by Rac/Cdc42 and can potentiate IKK-dependent NF-kappaB signaling.","uniprot_summary":"Probable guanine nucleotide exchange factor (GEF).","go_terms":{"molecular_function":[{"id":"GO:0005515","label":"protein binding"}],"biological_process":[{"id":"GO:0043123","label":"positive regulation of I-kappaB kinase/NF-kappaB signaling"},{"id":"GO:0051056","label":"regulation of small GTPase mediated signal transduction"}],"cellular_component":[{"id":"GO:0005829","label":"cytosol"}]},"interpro":[{"id":"IPR035899","name":"Dbl homology (DH) domain superfamily","type":"homologous_superfamily","start":279,"end":501},{"id":"IPR011993","name":"PH-like domain superfamily","type":"homologous_superfamily","start":510,"end":676},{"id":"IPR000219","name":"Dbl homology domain","type":"domain","start":288,"end":488},{"id":"IPR001849","name":"Pleckstrin homology domain","type":"domain","start":535,"end":670},{"id":"IPR040181","name":"Pleckstrin homology domain-containing family G member 5/7","type":"family","start":26,"end":674}],"reasoning":"I begin with the InterPro architecture. The core catalytic module is a Dbl homology (DH) domain superfamily signature IPR035899 spanning residues 279–501, within which a canonical Dbl homology domain (IPR000219) lies from residues 288–488. Immediately C-terminal to the DH core sits a Pleckstrin homology (PH) module annotated twice: a PH-like domain superfamily (IPR011993) from residues 510–676 and a specific Pleckstrin homology domain (IPR001849) from residues 535–670. This DH–PH tandem is the hallmark of Rho-family guanine nucleotide exchange factors (RhoGEFs). The N-to-C arrangement—DH followed by PH—creates a catalytic platform: the DH domain catalyzes GDP release from small GTPases, while the PH domain positions the enzyme at membrane-proximal signaling sites and stabilizes nucleotide exchange through lipid and protein contacts. The broader family assignment IPR040181 (Pleckstrin homology domain-containing family G member 5/7, residues 26–674) reinforces that this polypeptide belongs to the metazoan PLEKHG subgroup that targets Rho/Rac/Cdc42 pathways.\n\nThis DH–PH architecture causes guanine nucleotide exchange on small GTPases by presenting the DH catalytic surface and membrane-targeting PH surface in tandem. Such assemblies inherently rely on multivalent contacts with partner proteins, which supports GO:0005515 protein binding as a basal molecular function. The DH domain dictates GEF chemistry toward small GTPases, and the PH domain tunes localization and substrate selection; together they drive activation of signaling modules that feed into broader pathways.\n\nFrom this catalytic core, the biological processes follow. Activation of small GTPases is the initiating step of GO:0051056 regulation of small GTPase mediated signal transduction. The DH–PH-driven activation of Rac/Cdc42 pathways can feed into IKK complex assembly and NF-kappaB activation; thus the architecture provides a mechanistic route to GO:0043123 positive regulation of I-kappaB kinase/NF-kappaB signaling. In practice, DH–PH GEFs at membrane-proximal hubs can potentiate inflammatory and stress-responsive cascades by coupling Rac/Cdc42 activity to IKK activation.\n\nCellular placement is inferred from the soluble nature of DH–PH tandems and their recruitment to membrane-proximal complexes. The absence of transmembrane segments and the soluble catalytic architecture argue for a cytosolic pool, consistent with GO:0005829 cytosol, with transient membrane association mediated by the PH domain and local phosphoinositide composition.\n\nMechanistically, I hypothesize that this protein operates as a cytosolic DH–PH GEF that transiently docks at phosphoinositide-rich membranes to activate Rac/Cdc42. By assembling with IKK-pathway adaptors, it can amplify NF-kappaB signaling. Likely interaction partners include small GTPases (RAC1, CDC42, RHO family), membrane adaptors and scaffolds that concentrate signaling modules, and components of the IKK axis that sense Rac/Cdc42-driven cytoskeletal cues. This arrangement explains how a cytosolic DH–PH enzyme can positively regulate NF-kappaB while broadly governing small GTPase signaling networks.","category":"dark","control_evaluation":null,"validation_plan":null,"structure":{"source":"AlphaFold DB","pdb":"/structures/AF-Q6ZR37.pdb","alphafold":"https://alphafold.ebi.ac.uk/entry/Q6ZR37"},"links":{"uniprot":"https://www.uniprot.org/uniprotkb/Q6ZR37/entry","atlas":"/p/Q6ZR37"},"provenance":{"model":"BioReason-Pro (ESM3 esm3-sm-open-v1)","source_list":"Pharos Tdark","note":"AI prediction, not experimentally verified"}}