Affinage

RTF1

RNA polymerase-associated protein RTF1 homolog · UniProt Q92541

Length
710 aa
Mass
80.3 kDa
Annotated
2026-06-10
26 papers in source corpus 21 papers cited in narrative 21 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

RTF1 is a dissociable transcription elongation factor of the PAF1 complex that couples RNA Polymerase II elongation to cotranscriptional histone modification at active genes (PMID:11884586, PMID:11014804). It is recruited to transcribing chromatin through a conserved Spt5-interacting domain that directly binds the Cdk9-phosphorylated Spt5 C-terminal repeat domain, an interaction necessary and sufficient to tether PAF1C to active genes (PMID:23775116, PMID:24385927). A discrete ~90-residue histone modification domain (HMD) is sufficient to drive cotranscriptional H2B monoubiquitylation (H2BK123/K120) and, indirectly, downstream H3K4 and H3K79 methylation, requiring Rad6-Bre1; the HMD contacts the conserved N-terminal helix of the ubiquitin conjugase Rad6 and stimulates H2Bub even in a transcription-free reconstituted system (PMID:12876293, PMID:22699496, PMID:27840029, PMID:37216505). Structurally, the Plus3 domain associates with RPB12 and phospho-SPT5, while an extended helix arrangement with a C-terminal 'fastener' and a 'latch' reaching the Pol II bridge helix allosterically stimulates elongation (PMID:32541898, PMID:18184592). RTF1 additionally recruits the Chd1 nucleosome remodeler through a direct N-terminal interaction with the Chd1 CHCT domain, restraining cryptic transcription and shaping nucleosome positioning (PMID:40867051). In vivo RTF1 promotes promoter-proximal RNA Pol II pausing required for cardiac progenitor maturation and Th17 differentiation, with its histone-modifying and elongation roles supporting distinct gene-regulatory programs (PMID:41537425, PMID:40073106).

Mechanistic history

Synthesis pass · year-by-year structured walk · 15 steps
  1. 1997 Medium

    Established RTF1 as a nuclear regulator of transcription start-site selection, the first functional placement of an otherwise uncharacterized gene.

    Evidence Genetic suppressor screen of a TBP specificity mutant with immunofluorescence localization in yeast

    PMID:9234706

    Open questions at the time
    • No physical mechanism linking RTF1 to TBP or initiation defined
    • No interaction partners identified
  2. 2000 Medium

    Reframed RTF1 as a transcription elongation factor by genetically linking it to the elongation machinery.

    Evidence Synthetic lethality with elongation-factor genes and sensitivity to 6-azauracil/mycophenolic acid in yeast

    PMID:11014804

    Open questions at the time
    • Genetic interactions do not show physical association
    • Molecular function during elongation unresolved
  3. 2002 High

    Defined RTF1 as a physical subunit of the Paf1-Pol II complex, providing the molecular assembly it acts within.

    Evidence Tandem affinity purification/mass spectrometry and double-mutant epistasis in yeast

    PMID:11884586

    Open questions at the time
    • Stoichiometry and structural arrangement within PAF1C unknown
    • Recruitment mechanism to genes not addressed
  4. 2003 High

    Connected RTF1 to a chromatin output by showing it is required for H2B K123 ubiquitylation upstream of H3K4/H3K79 methylation.

    Evidence ChIP, histone-modification western blots, and deletion analysis in yeast

    PMID:12876293

    Open questions at the time
    • Direct versus indirect role in ubiquitylation not distinguished
    • No structural basis for the activity
  5. 2008 High

    Provided the first structural view of an RTF1 module and a candidate nucleic-acid binding activity for the Plus3 domain.

    Evidence NMR structure of human Plus3 with in vitro DNA/RNA binding assays

    PMID:18184592

    Open questions at the time
    • In vivo relevance of ssDNA binding unclear
    • Plus3 partners within the elongation complex not defined
  6. 2012 High

    Localized the histone-modification activity to a transferable 90-residue HMD that functions independently of other PAF1C subunits.

    Evidence Domain truncation/sufficiency, ChIP, histone-modification westerns, and DNA-binding fusion in yeast

    PMID:21441211 PMID:22699496

    Open questions at the time
    • Direct enzymatic partner of the HMD not yet identified
    • Mechanism of HMD chromatin association incomplete
  7. 2013 High

    Identified the recruitment mechanism: a conserved RTF1 domain binds the phospho-Spt5 CTR to tether PAF1C to active chromatin.

    Evidence In vitro binding, ChIP, and mutagenesis in yeast; phospho-dependent binding via Cdk9 in S. pombe

    PMID:23775116 PMID:24385927

    Open questions at the time
    • Species differences in PAF1C separability not reconciled
    • Coupling between recruitment and HMD activity not mechanistically linked
  8. 2015 Medium

    Demonstrated PAF1C-independent activities of human RTF1, separating its elongation/coactivator function from the complex.

    Evidence In vitro transcription, RNA-seq, ChIP, and mutational analysis in human cells

    PMID:26217014

    Open questions at the time
    • Direct effectors of Plus3-dependent coactivation undefined
    • Gene-selectivity determinants unknown
  9. 2016 High

    Proved the HMD directly contacts Rad6 and stimulates H2Bub independently of transcription, establishing a direct enzymatic mechanism.

    Evidence Crystal structure of the HMD, transcription-free in vitro reconstitution, in vivo crosslinking, and ChIP-exo

    PMID:27840029

    Open questions at the time
    • Precise Rad6 surface engaged not yet mapped at residue level (resolved later)
    • Regulation of HMD-Rad6 engagement in vivo unclear
  10. 2020 High

    Resolved how RTF1 engages the polymerase: the Plus3 domain binds RPB12/phospho-SPT5 and a latch reaches the bridge helix to allosterically stimulate elongation.

    Evidence Cryo-EM of the complete Pol II elongation complex with in vitro elongation assays and latch mutagenesis

    PMID:32366382 PMID:32541898

    Open questions at the time
    • Coordination of allosteric elongation stimulation with H2Bub timing unknown
    • Conformational dynamics of the latch not captured
  11. 2023 High

    Mapped the HMD interface to the conserved Rad6 N-terminal helix and proved separation-of-function, isolating H2BK123ub from other Rad6 roles.

    Evidence Crosslinking-MS, in vivo crosslinking, separation-of-function genetics, and RNA-seq in yeast

    PMID:37216505

    Open questions at the time
    • Whether this interface is conserved in metazoan RNF20/40 systems not addressed here
    • Quantitative contribution of HMD to genome-wide H2Bub not partitioned
  12. 2023 Medium

    Extended RTF1 function to organismal development, linking promoter-proximal pausing to cardiac progenitor maturation.

    Evidence Morpholino/knockout in zebrafish and mouse, ChIP-seq, and CDK9-inhibitor rescue (preprint)

    PMID:37873297

    Open questions at the time
    • Mechanistic link between pausing and progenitor arrest incomplete
    • Target genes mediating the phenotype not fully defined
  13. 2025 High

    Identified a direct RTF1-Chd1 interaction that controls remodeler distribution, nucleosome positioning, and cryptic transcription.

    Evidence Co-IP/pulldown, domain mapping, ChIP-seq, nucleosome positioning, and cryptic-transcription reporters; conservation tested in mouse CHD1/CHD2

    PMID:40867051

    Open questions at the time
    • How RTF1-Chd1 coordinates with HMD/elongation activities unresolved
    • In vivo dynamics of remodeler handoff not defined
  14. 2025 Medium

    Connected RTF1 HMD-driven H2Bub to immune cell fate and to circadian transcription, broadening its physiological reach.

    Evidence Conditional knockout with Th17/Treg differentiation assays and RNF40 epistasis; Co-IP, ChIP, and H3K4me3 with circadian behavior in Drosophila/U2OS cells

    PMID:40073106 PMID:41186576

    Open questions at the time
    • Direct target genes driving Th17 and clock phenotypes not fully enumerated
    • Whether circadian role requires HMD versus elongation activity unclear
  15. 2026 Medium

    Consolidated the in vivo pausing model, showing the Plus3-Spt5 interaction underlies cardiogenic Pol II pausing rescued by CDK9 inhibition.

    Evidence Zebrafish/mouse knockout, ChIP-seq, CDK9 morpholino and pharmacological rescue, and structure-function analysis

    PMID:41537425

    Open questions at the time
    • Causal chain from altered pausing to specific cardiac gene programs incomplete
    • Generality of pausing role across tissues not established

Open questions

Synthesis pass · forward-looking unresolved questions
  • How RTF1's distinct molecular activities — Spt5-dependent recruitment, allosteric elongation stimulation, HMD-driven H2Bub, and Chd1 recruitment — are integrated and differentially deployed across genes, tissues, and developmental programs remains unresolved.
  • No unified model partitioning RTF1's elongation versus chromatin activities by gene context
  • Determinants of gene-selective RTF1 dependence unknown
  • Metazoan structural basis for HMD-RNF20/40 engagement not directly resolved

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0098772 molecular function regulator activity 3 GO:0140110 transcription regulator activity 3 GO:0003677 DNA binding 1
Localization
GO:0005694 chromosome 3 GO:0005634 nucleus 1
Pathway
R-HSA-4839726 Chromatin organization 3 R-HSA-74160 Gene expression (Transcription) 2
Complex memberships
PAF1 complex

Evidence

Reading pass · 21 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1997 RTF1 was identified as a nuclear protein whose mutation or deletion suppresses transcription start site alterations caused by a TBP specificity mutant, placing RTF1 as a regulator of TBP-dependent TATA site selection in vivo. Genetic suppressor screen, indirect immunofluorescence localization, transcription initiation analysis Molecular and cellular biology Medium 9234706
2000 RTF1 functions as a transcription elongation factor, demonstrated by synthetic lethality with elongation factor genes (SPT4, SPT5, SPT16, PPR2, SRB5, CTK1, FCP1, POB3) and sensitivity to 6-azauracil and mycophenolic acid. Synthetic lethal screen, drug sensitivity assay (6-azauracil, mycophenolic acid), genetic epistasis Genetics Medium 11014804
2002 Rtf1, Ctr9, and Leo1 are components of the Paf1-RNA Pol II complex, physically associating with Paf1, Cdc73, and Pol II but not with the Srb-mediator complex; deletion of RTF1 suppresses many paf1Δ phenotypes including reduced CLN1 expression. Tandem affinity purification, mass spectrometry, genetic analysis of double mutants Molecular and cellular biology High 11884586
2003 Rtf1 is required for global histone H2B ubiquitination at K123, and this is the indirect mechanism by which Rtf1 promotes H3-K4 and H3-K79 methylation; Rtf1 is also required for Set1 recruitment to active genes for H3-K4 methylation but not for H3-K36 methylation. Chromatin immunoprecipitation, histone modification analysis by western blot, genetic deletion analysis The Journal of biological chemistry High 12876293
2008 The NMR structure of the human Rtf1 Plus3 domain reveals structural similarity to PAZ and Tudor domains; the Plus3 domain binds single-stranded DNA via basic residues on the rim of its beta sheet in vitro, but does not bind double-stranded DNA or RNA. NMR structure determination, in vitro DNA/RNA binding assay Structure High 18184592
2008 S. pombe Rtf1 (replication termination factor 1, a distinct protein from transcription factor Rtf1/Prf1) mediates site-specific replication termination at RTS1 via two myb/SANT DNA-binding domains and self-interaction through its C-terminal tail. NOTE: This paper describes the S. pombe replication termination Rtf1, which is a different protein from the transcription elongation Rtf1/Prf1 discussed in other papers. Domain characterization, DNA binding assays, genetic analysis with dominant-negative mutants Genetics Low 18723894
2011 Single amino acid substitutions within the Rtf1 histone modification domain (HMD) abolish H2B ubiquitylation and impair H3 methylation, and also disrupt 3'-end formation of snoRNA transcripts, identifying H2B K123 ubiquitylation as required for noncoding RNA termination. Site-directed mutagenesis, histone modification assays, snoRNA 3'-end analysis, telomeric silencing and elongation assays Genetics High 21441211
2012 A 90-amino acid histone modification domain (HMD) within Rtf1 is sufficient to promote H3 K4 and K79 methylation and H2B K123 ubiquitylation independently of other Paf1C subunits when expressed as the only source of Rtf1; this function requires Rad6-Bre1 and conserved HMD residues important for chromatin association. Domain truncation and expression analysis, chromatin immunoprecipitation, histone modification western blot, DNA binding domain fusion experiments PNAS High 22699496
2013 A conserved domain of Rtf1 (Spt5-interacting domain) directly and physically interacts with the Spt5 C-terminal repeat domain (CTR), and this interaction is necessary and sufficient for tethering Paf1C to active chromatin; mutations disrupting this interaction or deletion of the Spt5 CTR release Paf1C from chromatin. In vitro binding assay, ChIP, genetic mutations, domain sufficiency experiments Molecular and cellular biology High 23775116
2013 In S. pombe, Cdk9 phosphorylation of Spt5 creates a direct binding site for Prf1/Rtf1; Prf1 and the PAF complex are biochemically separable and exert opposing effects on the RNAPII elongation complex, with Prf1 negatively regulating elongation through H2B monoubiquitylation. Biochemical fractionation, genetic epistasis, phosphorylation-dependent binding assays PLoS genetics Medium 24385927
2015 Human Rtf1 functions as a transcription elongation factor independently of the PAF1 complex; its Plus3 domain is critical for coactivator-dependent transcription activation in vitro; human Rtf1 and PAF1C regulate distinct gene subsets and PAF1C is recruited to genes independently of Rtf1 in human cells. In vitro transcription assay, RNA-seq, ChIP, mutational analysis Molecular and cellular biology Medium 26217014
2016 The Rtf1 HMD directly interacts with the ubiquitin conjugase Rad6 and stimulates H2B monoubiquitylation independently of transcription; the crystal structure of the Rtf1 HMD was solved; site-specific in vivo crosslinking identified a conserved Rad6 interaction surface on the HMD; the HMD stimulates H2Bub in a transcription-free reconstituted in vitro system. Crystal structure determination, in vitro reconstitution, site-specific in vivo crosslinking, ChIP-exo, biochemical pulldown Molecular cell High 27840029
2020 Cryo-EM structure of the complete Pol II elongation complex reveals RTF1 Plus3 domain associates with RPB12 and phosphorylated SPT5 CTR; RTF1 forms four α-helices extending along the Pol II protrusion and RPB10 to the polymerase funnel; a C-terminal 'fastener' helix retains PAF and a 'latch' reaches the bridge helix; RTF1 strongly stimulates Pol II elongation, requiring the latch, suggesting allosteric activation of translocation. Cryo-EM structure determination, in vitro transcription elongation assay, structure-function mutagenesis Nature structural & molecular biology High 32541898
2020 In S. pombe, the Plus3 domain of Prf1/Rtf1 and phospho-Spt5 (pSpt5) function through parallel, distinct pathways to promote Prf1 function; the Plus3 domain has an alternate interface overlapping the pSpt5-binding site that can interact with single-stranded nucleic acid or PAF complex in vitro. Genetic epistasis, in vitro binding assay, domain mutational analysis Molecular and cellular biology Medium 32366382
2023 The Rtf1 HMD interaction surface on Rad6 was mapped to the highly conserved N-terminal helix of Rad6; separation-of-function mutations disrupting the Rad6-HMD interface impair H2BK123 ubiquitylation but not other Rad6 functions; RNA-seq profiles of these mutants overlap extensively with those of H2B ubiquitylation-site mutants. In vitro crosslinking followed by mass spectrometry, genetic separation-of-function mutations, in vivo protein crosslinking, RNA-seq PNAS High 37216505
2023 Rtf1 is essential for cardiogenesis in zebrafish and mammals; cardiac progenitors arrest in an immature state in rtf1 morphants/mutants; Rtf1's Plus3 domain (mediating Spt5 interaction) is required for cardiac progenitor formation; loss of Rtf1 reduces RNA Pol II occupancy at TSS of cardiac genes, reflecting reduced transcriptional pausing; pharmacological CDK9 inhibition restores cardiomyocyte formation in Rtf1-deficient embryos. Morpholino knockdown, genetic knockout (zebrafish and mouse), ChIP-seq, CDK9 inhibitor rescue experiments bioRxivpreprint Medium 37873297
2026 Rtf1 promotes promoter-proximal pausing of RNA Pol II; its Plus3 domain mediating Spt5 interaction is required for cardiogenic activity; in Rtf1-deficient zebrafish embryos RNA Pol II TSS occupancy is reduced relative to downstream occupancy, and CDK9 inhibition restores TSS occupancy and cardiomyocyte formation. Genetic knockout (zebrafish and mouse), ChIP-seq, CDK9 morpholino and pharmacological inhibition rescue, structure-function analysis eLife Medium 41537425
2025 An N-terminal region of Rtf1 directly interacts with the CHCT domain of Chd1 nucleosome remodeler; disruption of this interaction causes Chd1 accumulation at 5' gene ends, increased cryptic transcription, altered nucleosome positioning, and shifted histone modification profiles; a homologous region of mouse RTF1 also interacts with mouse CHD1 and CHD2 CHCT domains. Pull-down/co-IP interaction assays, domain mapping, mutagenesis, ChIP-seq, nucleosome positioning assays, cryptic transcription reporter Nucleic acids research High 40867051
2025 RTF1 physically interacts with CLOCK in Drosophila pacemaker neurons and promotes CLK occupancy at per and other clock gene promoters; SET1 forms a complex with CLK and RTF1 and increases H3K4me3 at per/tim promoters; human RTF1 physically interacts with BMAL1/CLOCK and affects circadian rhythms in U2OS cells. Co-immunoprecipitation, ChIP, H3K4me3 assays, genetic knockdown with behavioral rescue, overexpression rescue The Journal of cell biology Medium 41186576
2025 RTF1 facilitates histone H2B monoubiquitination (H2Bub1) through its HMD domain to support Th17 cell differentiation; cells lacking the H2Bub1 E3 ligase subunit RNF40 (a known RTF1 physical interactor) similarly impair Th17 differentiation, while Treg differentiation is unaffected. Conditional knockout, histone modification western blot, T cell differentiation assays, genetic epistasis with RNF40 Journal of immunology Medium 40073106
2025 RTF1 stimulates H2B-K120 ubiquitylation and H3K4me3 but RTF1 (unlike PAF1) does not contribute to transcription restart after DNA damage, dissociating RTF1's histone modification activity from the PAF1C-dependent transcription restoration function. Transcription recovery assay after UV damage, histone modification analysis, siRNA knockdown bioRxivpreprint Low bio_10.1101_2025.07.23.666359

Source papers

Stage 0 corpus · 26 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2003 The Rtf1 component of the Paf1 transcriptional elongation complex is required for ubiquitination of histone H2B. The Journal of biological chemistry 237 12876293
2002 Ctr9, Rtf1, and Leo1 are components of the Paf1/RNA polymerase II complex. Molecular and cellular biology 206 11884586
2020 Structure of complete Pol II-DSIF-PAF-SPT6 transcription complex reveals RTF1 allosteric activation. Nature structural & molecular biology 130 32541898
2000 Synthetic lethal interactions suggest a role for the Saccharomyces cerevisiae Rtf1 protein in transcription elongation. Genetics 110 11014804
2016 The Histone Modification Domain of Paf1 Complex Subunit Rtf1 Directly Stimulates H2B Ubiquitylation through an Interaction with Rad6. Molecular cell 90 27840029
1997 Identification of RTF1, a novel gene important for TATA site selection by TATA box-binding protein in Saccharomyces cerevisiae. Molecular and cellular biology 64 9234706
2013 The recruitment of the Saccharomyces cerevisiae Paf1 complex to active genes requires a domain of Rtf1 that directly interacts with the Spt4-Spt5 complex. Molecular and cellular biology 60 23775116
2012 Small region of Rtf1 protein can substitute for complete Paf1 complex in facilitating global histone H2B ubiquitylation in yeast. Proceedings of the National Academy of Sciences of the United States of America 54 22699496
2013 The PAF complex and Prf1/Rtf1 delineate distinct Cdk9-dependent pathways regulating transcription elongation in fission yeast. PLoS genetics 45 24385927
2015 Characterization of the Human Transcription Elongation Factor Rtf1: Evidence for Nonoverlapping Functions of Rtf1 and the Paf1 Complex. Molecular and cellular biology 42 26217014
2011 Identification of a role for histone H2B ubiquitylation in noncoding RNA 3'-end formation through mutational analysis of Rtf1 in Saccharomyces cerevisiae. Genetics 42 21441211
2008 Structure and DNA binding of the human Rtf1 Plus3 domain. Structure (London, England : 1993) 42 18184592
2008 Rtf1-mediated eukaryotic site-specific replication termination. Genetics 32 18723894
2023 Paf1 complex subunit Rtf1 stimulates H2B ubiquitylation by interacting with the highly conserved N-terminal helix of Rad6. Proceedings of the National Academy of Sciences of the United States of America 24 37216505
2020 Spt5 Phosphorylation and the Rtf1 Plus3 Domain Promote Rtf1 Function through Distinct Mechanisms. Molecular and cellular biology 8 32366382
2012 The Paf1 complex subunit Rtf1 buffers cells against the toxic effects of [PSI+] and defects in Rkr1-dependent protein quality control in Saccharomyces cerevisiae. Genetics 7 22595241
2025 A direct interaction between the Chd1 CHCT domain and Rtf1 controls Chd1 distribution and nucleosome positioning on active genes. Nucleic acids research 6 40867051
2023 Schizosaccharomyces pombe Rtf2 is important for replication fork barrier activity of RTS1 via splicing of Rtf1. eLife 4 37615341
2024 A direct interaction between the Chd1 CHCT domain and Rtf1 controls Chd1 distribution and nucleosome positioning on active genes. bioRxiv : the preprint server for biology 3 39677735
2023 Rtf1-dependent transcriptional pausing regulates cardiogenesis. bioRxiv : the preprint server for biology 2 37873297
2026 Rtf1-dependent transcriptional pausing regulates cardiogenesis. eLife 1 41537425
2025 RTF1 mediates epigenetic control of Th17 cell differentiation via H2B monoubiquitination. Journal of immunology (Baltimore, Md. : 1950) 1 40073106
2025 Rtf1 HMD domain facilitates global histone H2B monoubiquitination and regulates morphogenesis and virulence in the meningitis-causing pathogen Cryptococcus neoformans. eLife 1 40353352
2025 RTF1 enhances CLK occupancy and histone methylation at key circadian clock pacemaker gene loci. The Journal of cell biology 1 41186576
2023 Rtf1 Transcriptionally Regulates Neonatal and Adult Cardiomyocyte Biology. Journal of cardiovascular development and disease 1 37233188
2024 The Rtf1/Prf1-dependent histone modification axis counteracts multi-drug resistance in fission yeast. Life science alliance 0 38514187

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