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Li M, Yu H, Zhou B, Gan L, Li S, Zhang C, Yu B. JANUS, a spliceosome-associated protein, promotes miRNA biogenesis in Arabidopsis. Nucleic Acids Res 2024; 52:420-430. [PMID: 37994727 PMCID: PMC10783502 DOI: 10.1093/nar/gkad1105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/27/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023] Open
Abstract
MicroRNAs (miRNAs) are important regulators of genes expression. Their levels are precisely controlled through modulating the activity of the microprocesser complex (MC). Here, we report that JANUS, a homology of the conserved U2 snRNP assembly factor in yeast and human, is required for miRNA accumulation. JANUS associates with MC components Dicer-like 1 (DCL1) and SERRATE (SE) and directly binds the stem-loop of pri-miRNAs. In a hypomorphic janus mutant, the activity of DCL1, the numbers of MC, and the interaction of primary miRNA transcript (pri-miRNAs) with MC are reduced. These data suggest that JANUS promotes the assembly and activity of MC through its interaction with MC and/or pri-miRNAs. In addition, JANUS modulates the transcription of some pri-miRNAs as it binds the promoter of pri-miRNAs and facilitates Pol II occupancy of at their promoters. Moreover, global splicing defects are detected in janus. Taken together, our study reveals a novel role of a conserved splicing factor in miRNA biogenesis.
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Affiliation(s)
- Mu Li
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588–0666, USA
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588–0118, USA
| | - Huihui Yu
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588–0666, USA
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588–0118, USA
| | - Bangjun Zhou
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588–0666, USA
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588–0118, USA
| | - Lu Gan
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588–0666, USA
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588–0118, USA
| | - Shengjun Li
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Shandong Energy Institute, Qingdao New Energy Shangdong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Chi Zhang
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588–0666, USA
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588–0118, USA
| | - Bin Yu
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588–0666, USA
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588–0118, USA
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Larsen NA. The SF3b Complex is an Integral Component of the Spliceosome and Targeted by Natural Product-Based Inhibitors. Subcell Biochem 2021; 96:409-432. [PMID: 33252738 DOI: 10.1007/978-3-030-58971-4_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
In this chapter, the essential role of the SF3b multi-protein complex will be discussed in the context of the overall spliceosome. SF3b is critical during spliceosome assembly for recognition of the branch point (BP) adenosine and, by de facto, selection of the 3' splice site. This complex is highly dynamic, undergoing significant conformational changes upon loading of the branch duplex RNA and in its relative positioning during spliceosomal remodeling from the A, pre-B, B, Bact and B* complexes. Ultimately, during the spliceosome activation phase, SF3b must be displaced to unmask the branch point adenosine for the first splicing reaction to occur. In certain cancers, such as the hematological malignancies CML, CLL and MDS, the SF3b subunit SF3B1 is frequently mutated. Recent studies suggest these mutations lead to inappropriate branch point selection and mis-splicing events that appear to be drivers of disease. Finally, the SF3b complex is the target for at least three different classes of natural product-based inhibitors. These inhibitors bind in the BP adenosine-binding pocket and demonstrate a pre-mRNA competitive mechanism of action resulting in either intron retention or exon skipping. These compounds are extremely useful as chemical probes to isolate and characterize early stages of spliceosome assembly. They are also being explored preclinically and clinically as possible agents for hematological cancers.
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3
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Xiong F, Li S. SF3b4: A Versatile Player in Eukaryotic Cells. Front Cell Dev Biol 2020; 8:14. [PMID: 32083075 PMCID: PMC7002316 DOI: 10.3389/fcell.2020.00014] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 01/10/2020] [Indexed: 01/16/2023] Open
Abstract
Spliceosomes are large protein-RNA complexes regulating pre-mRNA processing in eukaryotes. SF3b4 encodes a core subunit of the U2-type spliceosome, loss- or gain-of-function of which often associates with abnormal cell growth, leading to tumorigenesis. Homologs of SF3b4 in other phyla are also essential. In this review, we summarize recent findings on the function of SF3b4. Importantly, we highlight the versatile roles of SF3b4, not only as a component for pre-mRNA splicing, but also as a regulator for transcription, translation, and cell signaling. Recent studies of SF3b4 homologs in different species across evolution will facilitate a better understanding of human diseases caused by the malfunction of SF3b4, such as Nager syndrome (NS) and cancer, in the future.
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Affiliation(s)
- Feng Xiong
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Sha Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.,Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tianjin, China
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4
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van der Feltz C, Hoskins AA. Structural and functional modularity of the U2 snRNP in pre-mRNA splicing. Crit Rev Biochem Mol Biol 2019; 54:443-465. [PMID: 31744343 DOI: 10.1080/10409238.2019.1691497] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The U2 small nuclear ribonucleoprotein (snRNP) is an essential component of the spliceosome, the cellular machine responsible for removing introns from precursor mRNAs (pre-mRNAs) in all eukaryotes. U2 is an extraordinarily dynamic splicing factor and the most frequently mutated in cancers. Cryo-electron microscopy (cryo-EM) has transformed our structural and functional understanding of the role of U2 in splicing. In this review, we synthesize these and other data with respect to a view of U2 as an assembly of interconnected functional modules. These modules are organized by the U2 small nuclear RNA (snRNA) for roles in spliceosome assembly, intron substrate recognition, and protein scaffolding. We describe new discoveries regarding the structure of U2 components and how the snRNP undergoes numerous conformational and compositional changes during splicing. We specifically highlight large scale movements of U2 modules as the spliceosome creates and rearranges its active site. U2 serves as a compelling example for how cellular machines can exploit the modular organization and structural plasticity of an RNP.
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Affiliation(s)
| | - Aaron A Hoskins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
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5
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Xiong F, Liu HH, Duan CY, Zhang BK, Wei G, Zhang Y, Li S. Arabidopsis JANUS Regulates Embryonic Pattern Formation through Pol II-Mediated Transcription of WOX2 and PIN7. iScience 2019; 19:1179-1188. [PMID: 31542701 PMCID: PMC6831869 DOI: 10.1016/j.isci.2019.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 04/07/2019] [Accepted: 09/04/2019] [Indexed: 02/06/2023] Open
Abstract
Embryonic pattern formation relies on positional coordination of cell division and specification. Early axis formation during Arabidopsis embryogenesis requires WUSCHEL RELATED HOMEOBOX (WOX)-mediated transcription activation and PIN-FORMED7 (PIN7)-mediated auxin asymmetry. How these events are regulated is obscure. We report that Arabidopsis JANUS, a putative subunit of spliceosome, is essential for embryonic pattern formation. Significantly reduced transcription but not mRNA processing of WOX2 and PIN7 in janus suggested its role in transcriptional regulation. JANUS interacts with RNA polymerase II (Pol II) through a region outside of its spliceosome-association domain. We further show that Pol II mediates the transcription of WOX2 and PIN7 in a JANUS-dependent way and is essential for embryonic pattern formation. These findings reveal that JANUS recruits Pol II for the activation of two parallel pathways to ensure proper pattern formation during embryogenesis. Arabidopsis JANUS, a putative spliceosome subunit, is essential for embryogenesis JANUS mediates the transcription but not RNA processing of WOX2 and PIN7 JANUS interacts with RNA polymerase II whose mutations caused embryo lethality Pol II mediates the transcription of WOX2 and PIN7 in a JANUS-dependent manner
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Affiliation(s)
- Feng Xiong
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Hai-Hong Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Cun-Ying Duan
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Bi-Ke Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Guo Wei
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Yan Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China
| | - Sha Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China; Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tianjin, China.
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6
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Zhang X, Yan C, Zhan X, Li L, Lei J, Shi Y. Structure of the human activated spliceosome in three conformational states. Cell Res 2018; 28:307-322. [PMID: 29360106 PMCID: PMC5835773 DOI: 10.1038/cr.2018.14] [Citation(s) in RCA: 137] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 01/02/2018] [Accepted: 01/08/2018] [Indexed: 12/13/2022] Open
Abstract
During each cycle of pre-mRNA splicing, the pre-catalytic spliceosome (B complex) is converted into the activated spliceosome (Bact complex), which has a well-formed active site but cannot proceed to the branching reaction. Here, we present the cryo-EM structure of the human Bact complex in three distinct conformational states. The EM map allows atomic modeling of nearly all protein components of the U2 small nuclear ribonucleoprotein (snRNP), including three of the SF3a complex and seven of the SF3b complex. The structure of the human Bact complex contains 52 proteins, U2, U5, and U6 small nuclear RNA (snRNA), and a pre-mRNA. Three distinct conformations have been captured, representing the early, mature, and late states of the human Bact complex. These complexes differ in the orientation of the Switch loop of Prp8, the splicing factors RNF113A and NY-CO-10, and most components of the NineTeen complex (NTC) and the NTC-related complex. Analysis of these three complexes and comparison with the B and C complexes reveal an ordered flux of components in the B-to-Bact and the Bact-to-B* transitions, which ultimately prime the active site for the branching reaction.
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Affiliation(s)
- Xiaofeng Zhang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Chuangye Yan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Xiechao Zhan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Lijia Li
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Jianlin Lei
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Technology Center for Protein Sciences, Ministry of Education Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.,Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Shilongshan Road No. 18, Hangzhou, Zhejiang 310064, China
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7
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Haselbach D, Komarov I, Agafonov DE, Hartmuth K, Graf B, Dybkov O, Urlaub H, Kastner B, Lührmann R, Stark H. Structure and Conformational Dynamics of the Human Spliceosomal B act Complex. Cell 2018; 172:454-464.e11. [PMID: 29361316 DOI: 10.1016/j.cell.2018.01.010] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/23/2017] [Accepted: 01/05/2018] [Indexed: 11/19/2022]
Abstract
The spliceosome is a highly dynamic macromolecular complex that precisely excises introns from pre-mRNA. Here we report the cryo-EM 3D structure of the human Bact spliceosome at 3.4 Å resolution. In the Bact state, the spliceosome is activated but not catalytically primed, so that it is functionally blocked prior to the first catalytic step of splicing. The spliceosomal core is similar to the yeast Bact spliceosome; important differences include the presence of the RNA helicase aquarius and peptidyl prolyl isomerases. To examine the overall dynamic behavior of the purified spliceosome, we developed a principal component analysis-based approach. Calculating the energy landscape revealed eight major conformational states, which we refined to higher resolution. Conformational differences of the highly flexible structural components between these eight states reveal how spliceosomal components contribute to the assembly of the spliceosome, allowing it to generate a dynamic interaction network required for its subsequent catalytic activation.
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Affiliation(s)
- David Haselbach
- Department for Structural Dynamics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Ilya Komarov
- Department for Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Dmitry E Agafonov
- Department for Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Klaus Hartmuth
- Department for Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Benjamin Graf
- Department for Structural Dynamics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Olexandr Dybkov
- Department for Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytic Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Str. 40, 37073 Göttingen, Germany
| | - Berthold Kastner
- Department for Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Reinhard Lührmann
- Department for Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
| | - Holger Stark
- Department for Structural Dynamics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
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8
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León B, Kashyap MK, Chan WC, Krug KA, Castro JE, La Clair JJ, Burkart MD. A Challenging Pie to Splice: Drugging the Spliceosome. Angew Chem Int Ed Engl 2017; 56:12052-12063. [PMID: 28371109 PMCID: PMC6311392 DOI: 10.1002/anie.201701065] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Indexed: 02/05/2023]
Abstract
Since its discovery in 1977, the study of alternative RNA splicing has revealed a plethora of mechanisms that had never before been documented in nature. Understanding these transitions and their outcome at the level of the cell and organism has become one of the great frontiers of modern chemical biology. Until 2007, this field remained in the hands of RNA biologists. However, the recent identification of natural product and synthetic modulators of RNA splicing has opened new access to this field, allowing for the first time a chemical-based interrogation of RNA splicing processes. Simultaneously, we have begun to understand the vital importance of splicing in disease, which offers a new platform for molecular discovery and therapy. As with many natural systems, gaining clear mechanistic detail at the molecular level is key towards understanding the operation of any biological machine. This minireview presents recent lessons learned in this emerging field of RNA splicing chemistry and chemical biology.
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Affiliation(s)
- Brian León
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
| | - Manoj K. Kashyap
- Moores Cancer Center and Department of Medicine, University of California, San Diego, La Jolla CA, 92093-0820 (USA)
| | - Warren C. Chan
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
| | - Kelsey A. Krug
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
| | - Januario E. Castro
- Moores Cancer Center and Department of Medicine, University of California, San Diego, La Jolla CA, 92093-0820 (USA)
| | - James J. La Clair
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
| | - Michael D. Burkart
- Department of Chemistry and Biochemistry, University of California, San Diego 9500, Gilman Drive, La Jolla CA, 92093-0358 (USA) ,
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9
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Plaschka C, Lin PC, Nagai K. Structure of a pre-catalytic spliceosome. Nature 2017; 546:617-621. [PMID: 28530653 PMCID: PMC5503131 DOI: 10.1038/nature22799] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/02/2017] [Indexed: 12/12/2022]
Abstract
Intron removal requires assembly of the spliceosome on precursor mRNA (pre-mRNA) and extensive remodelling to form the spliceosome's catalytic centre. Here we report the cryo-electron microscopy structure of the yeast Saccharomyces cerevisiae pre-catalytic B complex spliceosome at near-atomic resolution. The mobile U2 small nuclear ribonucleoprotein particle (snRNP) associates with U4/U6.U5 tri-snRNP through the U2/U6 helix II and an interface between U4/U6 di-snRNP and the U2 snRNP SF3b-containing domain, which also transiently contacts the helicase Brr2. The 3' region of the U2 snRNP is flexibly attached to the SF3b-containing domain and protrudes over the concave surface of tri-snRNP, where the U1 snRNP may reside before its release from the pre-mRNA 5' splice site. The U6 ACAGAGA sequence forms a hairpin that weakly tethers the 5' splice site. The B complex proteins Prp38, Snu23 and Spp381 bind the Prp8 N-terminal domain and stabilize U6 ACAGAGA stem-pre-mRNA and Brr2-U4 small nuclear RNA interactions. These results provide important insights into the events leading to active site formation.
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MESH Headings
- Base Sequence
- Biocatalysis
- Catalytic Domain
- Cryoelectron Microscopy
- Introns/genetics
- Models, Biological
- Models, Molecular
- Nuclear Proteins/chemistry
- Nuclear Proteins/metabolism
- Protein Binding
- Protein Domains
- Protein Stability
- RNA Helicases/chemistry
- RNA Helicases/metabolism
- RNA Helicases/ultrastructure
- RNA Precursors/genetics
- RNA Precursors/metabolism
- RNA Precursors/ultrastructure
- RNA Splice Sites/genetics
- RNA Splicing
- RNA Splicing Factors/chemistry
- RNA Splicing Factors/metabolism
- RNA, Small Nuclear/chemistry
- RNA, Small Nuclear/metabolism
- Ribonucleoprotein, U2 Small Nuclear/chemistry
- Ribonucleoprotein, U2 Small Nuclear/metabolism
- Ribonucleoprotein, U4-U6 Small Nuclear/chemistry
- Ribonucleoprotein, U4-U6 Small Nuclear/metabolism
- Ribonucleoprotein, U5 Small Nuclear/chemistry
- Ribonucleoprotein, U5 Small Nuclear/metabolism
- Ribonucleoproteins, Small Nuclear/chemistry
- Ribonucleoproteins, Small Nuclear/metabolism
- Saccharomyces cerevisiae/chemistry
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae Proteins/chemistry
- Saccharomyces cerevisiae Proteins/metabolism
- Saccharomyces cerevisiae Proteins/ultrastructure
- Spliceosomes/chemistry
- Spliceosomes/metabolism
- Spliceosomes/ultrastructure
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Affiliation(s)
- Clemens Plaschka
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
| | - Pei-Chun Lin
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
| | - Kiyoshi Nagai
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
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