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Open data
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Basic information
| Entry | Database: PDB / ID: 9k3v | |||||||||||||||||||||||||||
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| Title | Human RNA Polymerase III de novo transcribing complex 4 (TC4) | |||||||||||||||||||||||||||
Components |
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Keywords | TRANSCRIPTION/DNA/RNA / initiation transcribing complex / TRANSCRIPTION-DNA-RNA complex | |||||||||||||||||||||||||||
| Function / homology | Function and homology informationsnRNA-activating protein complex / snRNA transcription / transcription preinitiation complex assembly / snRNA transcription by RNA polymerase III / bent DNA binding / RNA polymerase III preinitiation complex assembly / RNA Polymerase III Chain Elongation / transcription factor TFIIIB complex / TFIIIC-class transcription factor complex binding / RNA Polymerase III Transcription Termination ...snRNA-activating protein complex / snRNA transcription / transcription preinitiation complex assembly / snRNA transcription by RNA polymerase III / bent DNA binding / RNA polymerase III preinitiation complex assembly / RNA Polymerase III Chain Elongation / transcription factor TFIIIB complex / TFIIIC-class transcription factor complex binding / RNA Polymerase III Transcription Termination / DNA/RNA hybrid binding / calcitonin gene-related peptide receptor activity / RNA polymerase transcription factor SL1 complex / RNA polymerase III type 3 promoter sequence-specific DNA binding / regulation of transcription by RNA polymerase I / regulation of transcription by RNA polymerase III / snRNA transcription by RNA polymerase II / RNA polymerase III general transcription initiation factor activity / RNA polymerase I core promoter sequence-specific DNA binding / RPAP3/R2TP/prefoldin-like complex / DNA polymerase III complex / RNA Polymerase III Transcription Initiation From Type 1 Promoter / RNA Polymerase III Transcription Initiation From Type 2 Promoter / RNA Polymerase III Transcription Initiation From Type 3 Promoter / transcription factor TFIIA complex / female germ cell nucleus / RNA Polymerase III Abortive And Retractive Initiation / Cytosolic sensors of pathogen-associated DNA / male pronucleus / female pronucleus / positive regulation of innate immune response / RNA polymerase II general transcription initiation factor binding / nucleobase-containing compound metabolic process / Abortive elongation of HIV-1 transcript in the absence of Tat / FGFR2 alternative splicing / transcription preinitiation complex / RNA Polymerase I Transcription Termination / MicroRNA (miRNA) biogenesis / Viral Messenger RNA Synthesis / Signaling by FGFR2 IIIa TM / RNA polymerase II general transcription initiation factor activity / transcription factor TFIID complex / RNA Pol II CTD phosphorylation and interaction with CE during HIV infection / RNA Pol II CTD phosphorylation and interaction with CE / HIV Transcription Initiation / RNA Polymerase II HIV Promoter Escape / Transcription of the HIV genome / RNA Polymerase II Promoter Escape / RNA Polymerase II Transcription Pre-Initiation And Promoter Opening / RNA Polymerase II Transcription Initiation / RNA Polymerase II Transcription Initiation And Promoter Clearance / Formation of the Early Elongation Complex / Formation of the HIV-1 Early Elongation Complex / transcription initiation at RNA polymerase III promoter / mRNA Capping / mRNA Splicing - Minor Pathway / PIWI-interacting RNA (piRNA) biogenesis / aryl hydrocarbon receptor binding / TFIIB-class transcription factor binding / Processing of Capped Intron-Containing Pre-mRNA / RNA Polymerase I Transcription Initiation / transcription by RNA polymerase III / Pausing and recovery of Tat-mediated HIV elongation / Tat-mediated HIV elongation arrest and recovery / RNA polymerase II transcribes snRNA genes / HIV elongation arrest and recovery / Pausing and recovery of HIV elongation / neuropeptide signaling pathway / positive regulation of transcription initiation by RNA polymerase II / Tat-mediated elongation of the HIV-1 transcript / Formation of HIV-1 elongation complex containing HIV-1 Tat / RNA polymerase I complex / transcription elongation by RNA polymerase I / RNA polymerase III complex / RNA polymerase II core promoter sequence-specific DNA binding / core promoter sequence-specific DNA binding / Formation of HIV elongation complex in the absence of HIV Tat / RNA polymerase II, core complex / tRNA transcription by RNA polymerase III / RNA polymerase II preinitiation complex assembly / transcription by RNA polymerase I / RNA Polymerase II Transcription Elongation / Formation of RNA Pol II elongation complex / RNA Polymerase II Pre-transcription Events / acrosomal vesicle / mRNA Splicing - Major Pathway / Inhibition of DNA recombination at telomere / positive regulation of interferon-beta production / TBP-class protein binding / SIRT1 negatively regulates rRNA expression / male germ cell nucleus / TP53 Regulates Transcription of DNA Repair Genes / transcription initiation at RNA polymerase II promoter / RNA Polymerase I Promoter Escape / DNA-templated transcription initiation / Transcriptional regulation by small RNAs / mRNA transcription by RNA polymerase II / euchromatin / protein-DNA complex / NoRC negatively regulates rRNA expression Similarity search - Function | |||||||||||||||||||||||||||
| Biological species | Homo sapiens (human) | |||||||||||||||||||||||||||
| Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.5 Å | |||||||||||||||||||||||||||
Authors | Wang, Q. / Ren, Y. / Jin, Q. / Chen, X. / Xu, Y. | |||||||||||||||||||||||||||
| Funding support | 1items
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Citation | Journal: Nature / Year: 2025Title: Structural insights into human Pol III transcription initiation in action. Authors: Qianmin Wang / Yulei Ren / Qianwei Jin / Xizi Chen / Yanhui Xu / ![]() Abstract: RNA polymerase III (Pol III) transcribes highly demanded RNAs grouped into three types of classical promoters, including type 1 (5S rRNA), type 2 (tRNA) and type 3 (short non-coding RNAs, such as U6, ...RNA polymerase III (Pol III) transcribes highly demanded RNAs grouped into three types of classical promoters, including type 1 (5S rRNA), type 2 (tRNA) and type 3 (short non-coding RNAs, such as U6, 7SK and RNase H1) promoters. While structures of the Pol III preinitiation complex (PIC) and elongation complex (EC) have been determined, the mechanism underlying the transition from initiation to elongation remains unclear. Here we reconstituted seven human Pol III transcribing complexes (TC4, TC5, TC6, TC8, TC10, TC12 and TC13) halted on U6 promoters with nascent RNAs of 4-13 nucleotides. Cryo-electron microscopy structures captured initially transcribing complexes (ITCs; TC4 and TC5) and ECs (TC6-13). Together with KMnO footprinting, the data reveal extensive modular rearrangements: the transcription bubble expands from PIC to TC5, followed by general transcription factor (GTF) dissociation and abrupt bubble collapse from TC5 to TC6, marking the ITC-EC transition. In TC5, SNAPc and TFIIIB remain bound to the promoter and Pol III, while the RNA-DNA hybrid adopts a tilted conformation with template DNA blocked by BRF2, a TFIIIB subunit. Hybrid forward translocation during ITC-EC transition triggers BRF2-finger retraction, GTF release and transcription-bubble collapse. Pol III then escapes the promoter while GTFs stay bound upstream, potentially enabling reinitiation. These findings reveal molecular insights into Pol III dynamics and reinitiation mechanisms on type 3 promoters of highly demanded small RNAs, with the earliest documented initiation-elongation transition for an RNA polymerase. | |||||||||||||||||||||||||||
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Structure visualization
| Structure viewer | Molecule: Molmil Jmol/JSmol |
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Downloads & links
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Download
| PDBx/mmCIF format | 9k3v.cif.gz | 1.3 MB | Display | PDBx/mmCIF format |
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| PDB format | pdb9k3v.ent.gz | 1 MB | Display | PDB format |
| PDBx/mmJSON format | 9k3v.json.gz | Tree view | PDBx/mmJSON format | |
| Others | Other downloads |
-Validation report
| Summary document | 9k3v_validation.pdf.gz | 1.6 MB | Display | wwPDB validaton report |
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| Full document | 9k3v_full_validation.pdf.gz | 1.7 MB | Display | |
| Data in XML | 9k3v_validation.xml.gz | 173.9 KB | Display | |
| Data in CIF | 9k3v_validation.cif.gz | 276.8 KB | Display | |
| Arichive directory | https://data.pdbj.org/pub/pdb/validation_reports/k3/9k3v ftp://data.pdbj.org/pub/pdb/validation_reports/k3/9k3v | HTTPS FTP |
-Related structure data
| Related structure data | ![]() 62030MC ![]() 9k2gC ![]() 9k36C ![]() 9k38C ![]() 9k39C ![]() 9k3bC ![]() 9k3uC ![]() 9lktC ![]() 9lxnC ![]() 9lxoC M: map data used to model this data C: citing same article ( |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
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Assembly
| Deposited unit | ![]()
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Components
-SnRNA-activating protein complex subunit ... , 3 types, 3 molecules 134
| #1: Protein | Mass: 43074.473 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: SNAPC1, SNAP43 / Production host: Homo sapiens (human) / References: UniProt: Q16533 |
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| #2: Protein | Mass: 46812.605 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: SNAPC3, SNAP50 / Production host: Homo sapiens (human) / References: UniProt: Q92966 |
| #3: Protein | Mass: 159645.172 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: SNAPC4, SNAP190 / Production host: Homo sapiens (human) / References: UniProt: Q5SXM2 |
-DNA-directed RNA polymerase III subunit ... , 10 types, 10 molecules ABDGIMNOPQ
| #4: Protein | Mass: 155860.125 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3A / Production host: Homo sapiens (human) / References: UniProt: O14802, DNA-directed RNA polymerase |
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| #5: Protein | Mass: 127953.891 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3B / Production host: Homo sapiens (human) / References: UniProt: Q9NW08, DNA-directed RNA polymerase |
| #7: Protein | Mass: 16893.990 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: CRCP / Production host: Homo sapiens (human) / References: UniProt: O75575 |
| #10: Protein | Mass: 22938.846 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3H, KIAA1665, RPC8 / Production host: Homo sapiens (human) / References: UniProt: Q9Y535 |
| #12: Protein | Mass: 12338.104 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3K, RPC11, My010 / Production host: Homo sapiens (human) / References: UniProt: Q9Y2Y1 |
| #16: Protein | Mass: 80004.031 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3E, KIAA1452 / Production host: Homo sapiens (human) / References: UniProt: Q9NVU0 |
| #17: Protein | Mass: 44471.875 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3D, BN51, BN51T / Production host: Homo sapiens (human) / References: UniProt: P05423 |
| #18: Protein | Mass: 60692.555 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3C / Production host: Homo sapiens (human) / References: UniProt: Q9BUI4 |
| #19: Protein | Mass: 35726.914 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3F / Production host: Homo sapiens (human) / References: UniProt: Q9H1D9 |
| #20: Protein | Mass: 25953.510 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR3G / Production host: Homo sapiens (human) / References: UniProt: O15318 |
-DNA-directed RNA polymerases I and III subunit ... , 2 types, 2 molecules CK
| #6: Protein | Mass: 39301.672 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR1C, POLR1E / Production host: Homo sapiens (human) / References: UniProt: O15160 |
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| #14: Protein | Mass: 15259.222 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR1D / Production host: Homo sapiens (human) / References: UniProt: P0DPB6 |
-DNA-directed RNA polymerases I, II, and III subunit ... , 5 types, 5 molecules EFHJL
| #8: Protein | Mass: 24584.223 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR2E / Production host: Homo sapiens (human) / References: UniProt: P19388 |
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| #9: Protein | Mass: 14491.026 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR2F, POLRF / Production host: Homo sapiens (human) / References: UniProt: P61218 |
| #11: Protein | Mass: 17162.273 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR2H / Production host: Homo sapiens (human) / References: UniProt: P52434 |
| #13: Protein | Mass: 7655.123 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR2L / Production host: Homo sapiens (human) / References: UniProt: P62875 |
| #15: Protein | Mass: 7018.244 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: POLR2K / Production host: Homo sapiens (human) / References: UniProt: P53803 |
-Transcription factor ... , 2 types, 2 molecules VW
| #22: Protein | Mass: 46587.355 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: BRF2, BRFU, PRO1470 / Production host: Homo sapiens (human) / References: UniProt: Q9HAW0 |
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| #23: Protein | Mass: 294301.375 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: BDP1, KIAA1241, KIAA1689, TFNR / Production host: Homo sapiens (human) / References: UniProt: A6H8Y1 |
-DNA chain , 2 types, 2 molecules XY
| #24: DNA chain | Mass: 29599.984 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) Homo sapiens (human) |
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| #25: DNA chain | Mass: 29618.012 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) Homo sapiens (human) |
-Protein / RNA chain , 2 types, 2 molecules UZ
| #21: Protein | Mass: 37729.938 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) Homo sapiens (human) / Gene: TBP, GTF2D1, TF2D, TFIID / Production host: Homo sapiens (human) / References: UniProt: P20226 |
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| #26: RNA chain | Mass: 911.596 Da / Num. of mol.: 1 / Source method: obtained synthetically / Source: (synth.) Homo sapiens (human) |
-Non-polymers , 5 types, 11 molecules 








| #27: Chemical | ChemComp-ZN / #28: Chemical | ChemComp-3AT / | #29: Chemical | ChemComp-SF4 / | #30: Chemical | ChemComp-MG / | #31: Chemical | ChemComp-GTP / | |
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-Details
| Has ligand of interest | N |
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| Has protein modification | N |
-Experimental details
-Experiment
| Experiment | Method: ELECTRON MICROSCOPY |
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| EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
| Component | Name: RNA polymerase III transcribing complex 4 / Type: COMPLEX / Details: RNA polymerase III in initiation stage / Entity ID: #1-#26 / Source: MULTIPLE SOURCES |
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| Source (natural) | Organism: Homo sapiens (human) |
| Source (recombinant) | Organism: Homo sapiens (human) |
| Buffer solution | pH: 8 |
| Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
| Vitrification | Cryogen name: ETHANE-PROPANE |
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Electron microscopy imaging
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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| Microscopy | Model: TFS KRIOS |
| Electron gun | Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM |
| Electron lens | Mode: DARK FIELD / Nominal defocus max: 2500 nm / Nominal defocus min: 1500 nm |
| Image recording | Electron dose: 50 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) |
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Processing
| CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION |
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| 3D reconstruction | Resolution: 3.5 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 235000 / Symmetry type: POINT |
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FIELD EMISSION GUN