Affinage

SRRM1

Serine/arginine repetitive matrix protein 1 · UniProt Q8IYB3

Length
904 aa
Mass
102.3 kDa
Annotated
2026-06-10
18 papers in source corpus 16 papers cited in narrative 16 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

SRRM1 (SRm160) is a nuclear matrix-associated serine/arginine-repeat protein that functions as a general splicing coactivator, bridging exonic splicing enhancer (ESE)-bound SR family activators with the snRNP spliceosome to promote pre-mRNA splicing (PMID:10339552, PMID:11747818). Within the SRm160/300 coactivator it is the catalytically critical subunit, as recombinant SRm160 alone rescues splicing of SRm160/300-dependent pre-mRNAs (PMID:10668804), and it interacts directly with U2 snRNP and a Tra2 homolog to couple ESE recognition to spliceosome assembly (PMID:10339552). Beyond splicing, SRRM1 stimulates mRNA 3'-end cleavage through association with CPSF, an activity mapped to its N-terminal PWI domain and shown to be independent of the exon junction complex (PMID:11739730, PMID:12944400, PMID:16159877). It localizes to nuclear speckle splicing domains via discrete spatial-targeting and matrix-binding domains and undergoes ATP-dependent release from these sites, consistent with a role in coupling splicing to mRNA export (PMID:12624182, PMID:15024032). SRRM1 additionally partitions into a distinct cohesin-associated complex containing SMC1alpha, SMC3, RAD21, and SA2 (PMID:16159877). Functionally, SRRM1 governs cancer-relevant alternative splicing decisions, promoting Ras-dependent CD44 variable exon inclusion via interaction with Sam68 and driving oncogenic isoform programs (including NUMB exon 9) that support proliferation and invasion [PMID:16354706, PMID:bio_10.1101_2025.08.20.671097]. Heterozygous truncating variants in SRRM1 impair neuronal proliferation, migration, and neurite outgrowth, establishing a role in nervous system development (PMID:41145827).

Mechanistic history

Synthesis pass · year-by-year structured walk · 14 steps
  1. 1999 High

    Established SRRM1 as a splicing coactivator that bridges ESE-bound activators to the spliceosome, answering how purine-rich enhancers communicate with the core splicing machinery.

    Evidence In vitro splicing with immunodepletion plus reciprocal co-IP of SRm160/300 with U2 snRNP and a Tra2 homolog

    PMID:10339552

    Open questions at the time
    • Did not define which subunit carries the activity
    • Structural basis of the U2/Tra2 bridging interaction unresolved
  2. 2000 High

    Identified SRm160 as the functionally critical subunit of the SRm160/300 coactivator, resolving the division of labor within the complex.

    Evidence Specific immunodepletion of SRm300 and rescue of splicing with recombinant SRm160

    PMID:10668804

    Open questions at the time
    • Role of SRm300 in the complex left unclear
    • No structural data on the heterodimer
  3. 2001 High

    Generalized SRRM1's coactivator role across diverse SR proteins and ESE sequences and demonstrated in vivo importance, answering whether the bridging function is enhancer-specific.

    Evidence Co-IP of multiple SR proteins with SRm160, randomized-ESE splicing, and RNAi epistasis in C. elegans

    PMID:11747818

    Open questions at the time
    • Direct vs. indirect nature of each SR protein contact not mapped
    • Did not identify endogenous target transcripts
  4. 2002 High

    Extended SRRM1 beyond splicing to mRNA 3'-end formation, showing it physically links to CPSF and can uncouple 3'-end processing from splicing.

    Evidence In vitro and in vivo 3'-end cleavage assays with overexpression and co-IP with CPSF

    PMID:11739730

    Open questions at the time
    • CPSF contact surface not defined at this stage
    • Physiological relevance of pre-mRNA uncoupling unclear
  5. 2003 High

    Defined the mechanistic and spatial basis of SRRM1 function: 3'-end stimulation is EJC-independent, and discrete domains target it to speckles and the nuclear lamina near mRNA exit sites.

    Evidence Tethered-function and in vitro cleavage assays with EJC assembly, C. elegans RNAi epistasis, and deletion-mutant localization imaging

    PMID:12581738 PMID:12624182 PMID:12944400

    Open questions at the time
    • PWI domain not yet pinpointed as the active element
    • How matrix targeting couples to processing unresolved
  6. 2004 Medium

    Revealed ATP-regulated dynamics at speckles, distinguishing mobile export-associated SRRM1 complexes from immobile splicing complexes.

    Evidence In vitro FRAP in digitonin-permeabilized cells comparing SRm160, RNPS1, and SRm300 mobility

    PMID:15024032

    Open questions at the time
    • Identity of the ATP-dependent release factor unknown
    • Single-lab novel FRAP system
  7. 2005 High

    Uncovered a cohesin-associated SRRM1 complex distinct from its splicing complex and localized the 3'-end activity to the PWI domain, broadening its interactome.

    Evidence Immunoaffinity MS, gradient fractionation, co-IP/co-localization, and combinatorial RNAi in C. elegans

    PMID:16159877

    Open questions at the time
    • Functional consequence of SRRM1-cohesin association undefined
    • Whether the two complexes interconvert is unknown
  8. 2006 High

    Connected SRRM1 to oncogenic splicing by showing Ras-dependent control of CD44 v5 inclusion via Sam68 and a direct effect on tumor invasiveness.

    Evidence siRNA knockdown, overexpression, co-IP with Sam68, RT-PCR splicing, and invasion assays

    PMID:16354706

    Open questions at the time
    • Mechanism linking Ras signaling to SRRM1 activity not defined
    • Breadth of Sam68-dependent targets unknown
  9. 2014 Medium

    Identified post-translational regulation of SRRM1 by LAMMER kinase DOA, linking phosphorylation to its activity in development and sex determination.

    Evidence In vitro kinase assay and Doa-allele genetic epistasis in Drosophila with embryonic localization imaging

    PMID:24907259

    Open questions at the time
    • Phosphosites on SRRM1 not mapped
    • Human kinase ortholog not tested
  10. 2017 Medium

    Showed an in vivo splicing-dependent role for SRRM1 in regulating period transcript levels and circadian rhythms in pacemaker neurons.

    Evidence Tissue-specific RNAi and spliced-vs-unspliced per rescue with behavioral assays in Drosophila

    PMID:28801530

    Open questions at the time
    • Direct binding to per pre-mRNA not shown
    • Conservation in mammalian clock not tested
  11. 2019 Medium

    Defined the RNA-binding preference of SRRM1 for exonic GCA/AAC repeats and linked sex-specific binding to alternative splicing of transformer.

    Evidence HITS-CLIP in Drosophila sex-specific cell lines with gel-shift and minigene validation

    PMID:29750417

    Open questions at the time
    • Human RNA-binding map not established
    • Structural basis of repeat recognition unknown
  12. 2025 Medium

    Positioned SRRM1 as a driver of an oncogenic splicing program shared with SRSF11, controlling NUMB exon 9 and other cancer targets to support proliferation and invasion.

    Evidence Genome-wide CRISPR screen with NUMB splicing reporter, knockdown, proteomics, RNA-seq, and proliferation/invasion assays in colorectal and lung cancer cells (preprint)

    PMID:bio_10.1101_2025.08.20.671097

    Open questions at the time
    • Direct vs. indirect target effects not fully separated
    • Preprint, single lab
  13. 2025 Medium

    Implicated SRRM1 in nervous system development through truncating variants that impair neuronal phenotypes in cells and flies.

    Evidence CRISPR-engineered truncating variants in neuronal cells plus Drosophila neuronal RNAi with viability and locomotion readouts

    PMID:41145827

    Open questions at the time
    • Splicing targets underlying the neuronal phenotype not defined
    • Human Mendelian disease classification not established in this entry
  14. 2025 Low

    Suggested SRRM1 is a phosphorylation target of the speckle kinase TAOK2 governing speckle integrity and SR protein-driven splicing.

    Evidence Phosphoproteomics after TAOK2 knockdown with speckle imaging and splicing readouts (preprint)

    PMID:bio_10.1101_2025.09.29.679379

    Open questions at the time
    • Direct kinase assay on SRRM1 not reported
    • Preprint, single lab

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the distinct SRRM1 complexes (splicing, 3'-end processing, cohesin-associated) are partitioned and regulated in human cells, and what signaling controls its switch between normal and oncogenic splicing programs, remains unresolved.
  • No human structural model of SRRM1 complexes
  • Regulatory inputs governing complex choice unknown
  • Genome-wide human RNA target map incomplete

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0140110 transcription regulator activity 3 GO:0003723 RNA binding 1
Localization
GO:0005634 nucleus 3 GO:0005654 nucleoplasm 2 GO:0005635 nuclear envelope 1
Pathway
R-HSA-8953854 Metabolism of RNA 3 R-HSA-1643685 Disease 2 R-HSA-74160 Gene expression (Transcription) 2
Complex memberships
SRm160/300 splicing coactivatorcohesin (SMC1alpha/SMC3/RAD21/SA2)-associated complex

Evidence

Reading pass · 16 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1999 SRm160/300 splicing coactivator is required for a purine-rich exonic splicing enhancer (ESE) to promote splicing of a Drosophila doublesex pre-mRNA. SRm160/300 independently interacts with U2 snRNP and with a human homolog of Transformer 2 (which binds purine-rich ESEs), suggesting it bridges ESE-bound activators with the snRNP spliceosome machinery. In vitro splicing assays with immunodepletion, co-immunoprecipitation of SRm160/300 with U2 snRNP and Tra2 homolog Proceedings of the National Academy of Sciences of the United States of America High 10339552
2000 SRm160 is the more critical subunit of the SRm160/300 coactivator for splicing of SRm160/300-dependent pre-mRNAs. Specific depletion of SRm300 does not prevent splicing, whereas addition of recombinant SRm160 alone to SRm160/300-depleted reactions specifically activates splicing. Specific immunodepletion of SRm300 from splicing extracts; rescue with recombinant SRm160; cDNA isolation and sequence analysis of SRm300 RNA (New York, N.Y.) High 10668804
2001 SRm160 functions as a general splicing coactivator by interacting with multiple SR family proteins bound to diverse ESE sequences. Multiple SR family and SR-related proteins co-immunoprecipitate specifically with SRm160 under low-salt conditions. Genetic epistasis in C. elegans shows that simultaneous RNAi of CeSRm160 and any individual CeSR family gene produces unfertilized oocytes, demonstrating critical functional interactions in vivo. Co-immunoprecipitation of SR proteins with SRm160; RNA interference (RNAi) genetic epistasis in C. elegans; in vitro splicing with randomized ESE sequences Current biology : CB High 11747818
2002 SRm160 participates in mRNA 3'-end formation: overexpression promotes 3'-end cleavage in vivo and in vitro. At high levels, SRm160 activates 3'-end cleavage and cytoplasmic accumulation of unspliced pre-mRNAs, uncoupling the splicing requirement for 3'-end formation and nuclear export. SRm160 associates specifically with the cleavage polyadenylation specificity factor (CPSF) and stimulates cleavage of splicing-active pre-mRNAs more efficiently than splicing-inactive ones. In vivo overexpression assays; in vitro 3'-end cleavage assays; co-immunoprecipitation of SRm160 with CPSF Molecular and cellular biology High 11739730
2003 SRm160 is associated with the nuclear matrix and co-immunoprecipitates with TLS/FUS along with splicing factors PTB (hnRNPI) and SR proteins (SC35, SRp75), suggesting SRm160 participates in spliceosome assembly within the nuclear matrix context. Co-immunoprecipitation from nuclear extracts; co-immunolocalization; splicing assays with TLS/FUS-immunodepleted extracts Experimental cell research Medium 12581738
2003 SRm160 contains two contiguous domains (amino acids 300–350 and 351–688) that independently target it to nuclear matrix sites at splicing speckled domains. The N-terminal domain localizes SRm160 to the nuclear lamina near sites where mRNA exits the nucleus. These domains were identified as the spatial targeting and nuclear matrix binding domains. Fluorescence microscopy of FLAG- and EGFP-tagged deletion mutant proteins transfected into cells; nuclear matrix binding assays Proceedings of the National Academy of Sciences of the United States of America Medium 12624182
2003 SRm160 stimulates 3'-end cleavage independently of its association with the exon junction complex (EJC). EJC components RNPS1, REF, UAP56, and Y14 interact with SRm160, but only SRm160 and RNPS1 stimulate 3'-end cleavage when tethered to transcripts. Assembly of an EJC adjacent to the cleavage/polyadenylation signal in vitro did not significantly affect cleavage efficiency. In C. elegans, simultaneous RNAi of SRm160 and cleavage factor CstF-50 caused late embryonic arrest, demonstrating an evolutionarily conserved functional interaction between SRm160 and the 3'-end cleavage machinery. In vitro tethered-function assays; in vitro 3'-end cleavage assays with EJC assembly; RNAi epistasis in C. elegans The Journal of biological chemistry High 12944400
2004 SRm160 has ATP-dependent nuclear mobility at splicing speckled domains, revealed by in vitro FRAP in digitonin-permeabilized cells. Both EGFP-labeled and endogenous SRm160 are released from speckle sites by an ATP-dependent mechanism, suggesting SRm160-containing RNA export complexes (but not splicing complexes) have ATP-regulated release. In contrast, SRm300 remains immobile after ATP supplementation. In vitro FRAP (fluorescence recovery after photobleaching) in digitonin-permeabilized cells; comparison of EGFP-SRm160, endogenous SRm160, RNPS1, and SRm300 mobility The Journal of cell biology Medium 15024032
2005 SRm160-containing complexes are associated with cohesin subunits SMC1alpha, SMC3, RAD21, and SA2. Gradient fractionation revealed two predominant SRm160 complexes: one enriched in splicing components and another enriched in cohesin subunits. Co-immunoprecipitation, co-localization, and combinatorial RNAi in C. elegans support conserved functional interactions between SRm160 and cohesin. SRm160's N-terminal PWI domain mediates its 3'-end processing stimulatory activity. Immunoaffinity purification + tandem mass spectrometry (gel-free); gradient fractionation; co-immunoprecipitation; co-localization; combinatorial RNAi in C. elegans The Journal of biological chemistry High 16159877
2006 SRm160 regulates CD44 alternative splicing in a Ras-dependent manner: overexpression of SRm160 stimulates inclusion of CD44 variable exon 5 (v5) when Ras is activated, while siRNA-mediated silencing of SRm160 reduces v5 inclusion. SRm160 co-immunoprecipitates with Sam68, a protein that also stimulates v5 inclusion in a Ras-dependent manner, indicating these two proteins interact to regulate CD44 splicing. siRNA depletion of SRm160 reduces CD44 isoform levels and decreases tumor cell invasiveness. siRNA knockdown; overexpression; co-immunoprecipitation (SRm160 with Sam68); RT-PCR splicing assays; invasion assays Molecular and cellular biology High 16354706
2014 In Drosophila, SRm160 is phosphorylated in vitro by the LAMMER kinase DOA, and DOA kinase alleles suppress overexpression phenotypes of SRm160 in the eye while enhancing genital disc phenotypes, indicating DOA-mediated phosphorylation modifies SRm160 activity. SRm160 overexpression causes apoptosis in the Drosophila eye and is required for somatic sex determination. SRm160 protein is concentrated in nuclei of precellular embryos but is rapidly excluded or degraded upon cellularization. In vitro kinase assay (DOA phosphorylates SRm160); genetic epistasis (Doa alleles modifying SRm160 overexpression/loss-of-function phenotypes); immunofluorescence localization in embryos Genetics Medium 24907259
2017 In Drosophila, SRm160 is required in pacemaker neurons for proper circadian oscillations. Reduced SRm160 in adult pacemaker neurons impairs locomotor circadian rhythms and markedly reduces period (per) mRNA levels. The arrhythmicity is rescued by a fully spliced per construct but not by an extra copy of the endogenous per locus, demonstrating that SRm160 positively regulates per levels in a splicing-dependent manner. Tissue-specific RNAi knockdown in pacemaker neurons; genetic rescue with spliced vs. unspliced per constructs; behavioral assays; neuropeptide immunostaining (PDF/PIGMENT DISPERSING FACTOR) Genetics Medium 28801530
2019 SRm160 preferentially binds to exonic trinucleotide repeats GCA and AAC, as identified by HITS-CLIP in Drosophila sex-specific cell lines (S2 male, Kc female). Binding was validated by in vitro gel-shift assays and in vivo minigene splicing assays. SRm160 regulates alternative splicing of the sex-determination factor transformer, and 492 differential binding sites between male and female cells were identified, enriched for splicing factor transcripts. HITS-CLIP (high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation); in vitro gel-shift assay; minigene splicing assays; fly mutant analysis Journal of molecular cell biology Medium 29750417
2025 SRRM1 promotes an alternative splicing program favoring oncogenic isoforms including NUMB exon 9, identified in a genome-wide CRISPR screen. SRRM1 and SRSF11 share common protein interactors, RNA targets, and oncogenic splicing effects on targets including CD44, MKNK2, ECT2, DIAPH1, KAT5, TCF7L2, FOXM1, and TBX3. Loss of SRRM1 reduces Cyclin D1, Notum, and PRDX2 expression and decreases proliferation, colony formation, and invasion in colorectal and lung cancer cells. Genome-wide CRISPR screen with NUMB exon 9 splicing reporter; siRNA/shRNA knockdown; proteomics for shared interactors; RNA-seq for splicing targets; cell proliferation, colony formation, and invasion assays bioRxivpreprint Medium bio_10.1101_2025.08.20.671097
2025 SRRM1 (and SRRM2) are potential direct phosphorylation targets of the nuclear speckle-localized kinase TAOK2, as revealed by phosphoproteomics. TAOK2 knockdown perturbs nearly all speckle-resident SR-rich proteins while leaving hnRNPs unperturbed, suggesting SRRM1/2 phosphorylation by TAOK2 plays a structural maintenance role at nuclear speckles that impacts SR protein-driven exon inclusion. Phosphoproteomics after siRNA knockdown of TAOK2; siRNA knockdown functional readouts (alternative splicing, export, transcript abundance); nuclear speckle imaging bioRxivpreprint Low bio_10.1101_2025.09.29.679379
2025 Heterozygous truncating variants in SRRM1 (introduced via CRISPR-Cas9) cause impaired proliferation, migration, and neurite outgrowth in SKNBE2 neuronal cells differentiated in vitro. Pan-neuronal knockdown of Drosophila Srrm1 reduces viability, and motoneuronal knockdown impairs neurological function, establishing a role for SRRM1 in nervous system development. CRISPR-Cas9 introduction of truncating variants; neuronal differentiation assays; cell proliferation, migration, and neurite morphology quantification; Drosophila pan-neuronal and motoneuronal RNAi knockdown with viability and locomotion assays European journal of human genetics : EJHG Medium 41145827

Source papers

Stage 0 corpus · 18 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2006 Regulation of CD44 alternative splicing by SRm160 and its potential role in tumor cell invasion. Molecular and cellular biology 166 16354706
2000 The SRm160/300 splicing coactivator subunits. RNA (New York, N.Y.) 98 10668804
2003 Proto-oncoprotein TLS/FUS is associated to the nuclear matrix and complexed with splicing factors PTB, SRm160, and SR proteins. Experimental cell research 88 12581738
2002 SRm160 splicing coactivator promotes transcript 3'-end cleavage. Molecular and cellular biology 86 11739730
1999 The SRm160/300 splicing coactivator is required for exon-enhancer function. Proceedings of the National Academy of Sciences of the United States of America 72 10339552
2003 The spatial targeting and nuclear matrix binding domains of SRm160. Proceedings of the National Academy of Sciences of the United States of America 56 12624182
2003 An evolutionarily conserved role for SRm160 in 3'-end processing that functions independently of exon junction complex formation. The Journal of biological chemistry 38 12944400
2001 Multiple interactions between SRm160 and SR family proteins in enhancer-dependent splicing and development of C. elegans. Current biology : CB 38 11747818
2005 Proteomic analysis of SRm160-containing complexes reveals a conserved association with cohesin. The Journal of biological chemistry 29 16159877
2004 In vitro FRAP reveals the ATP-dependent nuclear mobilization of the exon junction complex protein SRm160. The Journal of cell biology 28 15024032
2022 SRRM1 promotes the proliferation, migration, and invasion of hepatocellular carcinoma cells by regulating the JAK/STAT signaling pathway. Tissue & cell 16 36270072
2022 A convergent malignant phenotype in B-cell acute lymphoblastic leukemia involving the splicing factor SRRM1. NAR cancer 12 36518527
2014 Multifunctional RNA processing protein SRm160 induces apoptosis and regulates eye and genital development in Drosophila. Genetics 9 24907259
2017 Rhythmic Behavior Is Controlled by the SRm160 Splicing Factor in Drosophila melanogaster. Genetics 7 28801530
2019 HITS-CLIP reveals sex-differential RNA binding and alterative splicing regulation of SRm160 in Drosophila. Journal of molecular cell biology 6 29750417
2025 A Prion-Like Domain in EBV EBNA1 Promotes Phase Separation and Enables SRRM1 Splicing. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 3 40729735
2025 Heterozygous loss of SRRM1 may be associated with neurodevelopmental phenotypes and anomalies in cell growth and neurite morphology. European journal of human genetics : EJHG 1 41145827
2024 Clinical value of circulating splicing factors in prostate cancer: SRRM1 as a novel predictive biomarker and therapeutic target. Molecular therapy. Oncology 0 39758250

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