u1 small nuclear ribonucleoprotein


Summary: A nuclear RNA-protein complex that plays a role in RNA processing. In the nucleoplasm, the U1 snRNP along with other small nuclear ribonucleoproteins (U2, U4-U6, and U5) assemble into SPLICEOSOMES that remove introns from pre-mRNA by splicing. The U1 snRNA forms base pairs with conserved sequence motifs at the 5'-splice site and recognizes both the 5'- and 3'-splice sites and may have a fundamental role in aligning the two sites for the splicing reaction.

Top Publications

  1. Zhang D, Rosbash M. Identification of eight proteins that cross-link to pre-mRNA in the yeast commitment complex. Genes Dev. 1999;13:581-92 pubmed
  2. Allain F, Howe P, Neuhaus D, Varani G. Structural basis of the RNA-binding specificity of human U1A protein. EMBO J. 1997;16:5764-72 pubmed
    ..This analysis provides a novel picture of RNA-protein recognition, much closer to our current understanding of protein-protein recognition than that of DNA-protein recognition. ..
  3. Förch P, Puig O, Martínez C, Seraphin B, Valcarcel J. The splicing regulator TIA-1 interacts with U1-C to promote U1 snRNP recruitment to 5' splice sites. EMBO J. 2002;21:6882-92 pubmed
    The U1 small nuclear ribonucleoprotein (U1 snRNP) binds to the pre-mRNA 5' splice site (ss) at early stages of spliceosome assembly...
  4. Shin C, Feng Y, Manley J. Dephosphorylated SRp38 acts as a splicing repressor in response to heat shock. Nature. 2004;427:553-8 pubmed
    ..We further show that dephosphorylated SRp38 interacts with a U1 small nuclear ribonucleoprotein particle (snRNP) protein, and that this interaction interferes with 5'-splice-site recognition by ..
  5. Shiels J, Tuite J, Nolan S, Baranger A. Investigation of a conserved stacking interaction in target site recognition by the U1A protein. Nucleic Acids Res. 2002;30:550-8 pubmed
  6. Du H, Rosbash M. The U1 snRNP protein U1C recognizes the 5' splice site in the absence of base pairing. Nature. 2002;419:86-90 pubmed
    ..in mammals, which engages the pre-mRNA in the splicing pathway and involves interactions between U1 small nuclear ribonucleoprotein (snRNP) and the pre-mRNA 5' splice site...
  7. Kormos B, Baranger A, Beveridge D. Do collective atomic fluctuations account for cooperative effects? Molecular dynamics studies of the U1A-RNA complex. J Am Chem Soc. 2006;128:8992-3 pubmed
    ..Predictions of additional sites in U1A that may be involved in cooperative networks are advanced. ..
  8. Law M, Chambers E, Katsamba P, Haworth I, Laird Offringa I. Kinetic analysis of the role of the tyrosine 13, phenylalanine 56 and glutamine 54 network in the U1A/U1 hairpin II interaction. Nucleic Acids Res. 2005;33:2917-28 pubmed
    The A protein of the U1 small nuclear ribonucleoprotein particle, interacting with its stem-loop RNA target (U1hpII), is frequently used as a paradigm for RNA binding by recognition motif domains (RRMs)...
  9. Jantsch M, Gall J. Assembly and localization of the U1-specific snRNP C protein in the amphibian oocyte. J Cell Biol. 1992;119:1037-46 pubmed
    ..In transfected tissue culture cells, the myc-tagged C protein localized within the nucleus in a speckled pattern similar to that of endogenous U1 snRNPs. ..

More Information


  1. Newkirk M, van Venrooij W, Marshall G. Autoimmune response to U1 small nuclear ribonucleoprotein (U1 snRNP) associated with cytomegalovirus infection. Arthritis Res. 2001;3:253-8 pubmed
    The induction of autoantibodies to U1 small nuclear ribonucleoprotein (U1 snRNP) complexes is not well understood...
  2. Lam B, Hertel K. A general role for splicing enhancers in exon definition. RNA. 2002;8:1233-41 pubmed
    ..Our results suggest that ESEs recruit a multicomponent complex that minimally contains components of the splicing machinery required for 5' and 3' splice site selection. ..
  3. McConnell T, Lokken R, Steitz J. Assembly of the U1 snRNP involves interactions with the backbone of the terminal stem of U1 snRNA. RNA. 2003;9:193-201 pubmed
    ..in two adenosines, A65 and A70, in the loop region previously identified as the binding site for the U1 small nuclear ribonucleoprotein (snRNP)-specific U1A protein...
  4. Hetzer M, Mattaj I. An ATP-dependent, Ran-independent mechanism for nuclear import of the U1A and U2B" spliceosome proteins. J Cell Biol. 2000;148:293-303 pubmed
    ..This activity can be solubilized in the presence of elevated MgCl(2). These data suggest that U1A and U2B" import into the nucleus occurs by a hitherto uncharacterized mechanism. ..
  5. Abovich N, Rosbash M. Cross-intron bridging interactions in the yeast commitment complex are conserved in mammals. Cell. 1997;89:403-12 pubmed
    ..Our results show that SF1 interacts strongly with human U2AF65, and that SF1 is a bona fide E complex component. This implies that aspects of these novel cross-intron protein-protein interactions are conserved between yeast and mammals. ..
  6. Golovkin M, Reddy A. The plant U1 small nuclear ribonucleoprotein particle 70K protein interacts with two novel serine/arginine-rich proteins. Plant Cell. 1998;10:1637-48 pubmed
    The U1 small nuclear ribonucleoprotein particle (U1 snRNP) 70K protein (U1-70K), one of the three U1 snRNP-specific proteins, is implicated in basic and alternative splicing of nuclear pre-mRNAs...
  7. Varani L, Gunderson S, Mattaj I, Kay L, Neuhaus D, Varani G. The NMR structure of the 38 kDa U1A protein - PIE RNA complex reveals the basis of cooperativity in regulation of polyadenylation by human U1A protein. Nat Struct Biol. 2000;7:329-35 pubmed
    ..This mechanism ensures that the activity of PAP enzyme, which is essential to the cell, is only down regulated when U1A is bound to the U1A mRNA. ..
  8. Kohtz J, Jamison S, Will C, Zuo P, Luhrmann R, Garcia Blanco M, et al. Protein-protein interactions and 5'-splice-site recognition in mammalian mRNA precursors. Nature. 1994;368:119-24 pubmed
    ..This cooperation is probably achieved by specific interactions between the arginine/serine-rich domain of the splicing factor and a similar region in a U1 snRNP-specific protein. ..
  9. Gasch A, Wiesner S, Martin Malpartida P, Ramirez Espain X, Ruiz L, Macias M. The structure of Prp40 FF1 domain and its interaction with the crn-TPR1 motif of Clf1 gives a new insight into the binding mode of FF domains. J Biol Chem. 2006;281:356-64 pubmed
    ..Our results also revealed that not all FF domains in Prp40 are functionally equivalent. We proposed that at least two different interaction surfaces exist in FF domains that have evolved to recognize distinct binding motifs. ..
  10. Hochleitner E, Kastner B, Frohlich T, Schmidt A, Luhrmann R, Arnold G, et al. Protein stoichiometry of a multiprotein complex, the human spliceosomal U1 small nuclear ribonucleoprotein: absolute quantification using isotope-coded tags and mass spectrometry. J Biol Chem. 2005;280:2536-42 pubmed
    ..These data demonstrate that quantitative mass spectrometry has great potential for the determination of the stoichiometry of multiprotein complexes. ..
  11. Hof D, Cheung K, de Rooij D, van den Hoogen F, Pruijn G, van Venrooij W, et al. Autoantibodies specific for apoptotic U1-70K are superior serological markers for mixed connective tissue disease. Arthritis Res Ther. 2005;7:R302-9 pubmed
    ..Patients suffering from mixed connective tissue disease (MCTD) produce autoantibodies directed to U1 small nuclear ribonucleoprotein (snRNP), and antibodies against a 70 kDa protein component, the U1-70K (70K) protein, are the most ..
  12. Benitex Y, Baranger A. Recognition of essential purines by the U1A protein. BMC Biochem. 2007;8:22 pubmed
  13. Lorkovic Z, Hilscher J, Barta A. Co-localisation studies of Arabidopsis SR splicing factors reveal different types of speckles in plant cell nuclei. Exp Cell Res. 2008;314:3175-86 pubmed publisher
  14. Price S, Evans P, Nagai K. Crystal structure of the spliceosomal U2B"-U2A' protein complex bound to a fragment of U2 small nuclear RNA. Nature. 1998;394:645-50 pubmed
  15. Förch P, Merendino L, Martínez C, Valcarcel J. U2 small nuclear ribonucleoprotein particle (snRNP) auxiliary factor of 65 kDa, U2AF65, can promote U1 snRNP recruitment to 5' splice sites. Biochem J. 2003;372:235-40 pubmed
    ..The arginine- and serine-rich domain of U2AF(65) is critical for U1 recruitment, and we discuss the role of its RNA-RNA annealing activity in this novel function of U2AF(65). ..
  16. Chen J, Stands L, Staley J, Jackups R, Latus L, Chang T. Specific alterations of U1-C protein or U1 small nuclear RNA can eliminate the requirement of Prp28p, an essential DEAD box splicing factor. Mol Cell. 2001;7:227-32 pubmed
    ..to counteract the stabilizing effect of the U1-C protein, thereby promoting the dissociation of the U1 small nuclear ribonucleoprotein particle from the 5' splice site...
  17. Murphy M, Olson B, Siliciano P. The yeast splicing factor Prp40p contains functional leucine-rich nuclear export signals that are essential for splicing. Genetics. 2004;166:53-65 pubmed
  18. Monneaux F, Lozano J, Patarroyo M, Briand J, Muller S. T cell recognition and therapeutic effect of a phosphorylated synthetic peptide of the 70K snRNP protein administered in MR/lpr mice. Eur J Immunol. 2003;33:287-96 pubmed
    ..We further demonstrated that P140 is recognized by antibodies from lupus patients and binds to various HLA DR molecules, offering new hope for manipulating T cell response in humans...
  19. Palfi Z, Lane W, Bindereif A. Biochemical and functional characterization of the cis-spliceosomal U1 small nuclear RNP from Trypanosoma brucei. Mol Biochem Parasitol. 2002;121:233-43 pubmed
    ..The 5' end of U1 snRNA in the U1 snRNP is accessible for and functional in specific recognition of the 5' splice site of the poly(A) polymerase intron. ..
  20. Wu X, Molinaro C, Johnson N, Casiano C. Secondary necrosis is a source of proteolytically modified forms of specific intracellular autoantigens: implications for systemic autoimmunity. Arthritis Rheum. 2001;44:2642-52 pubmed
  21. Hoet R, Raats J, de Wildt R, Dumortier H, Muller S, Van Den Hoogen F, et al. Human monoclonal autoantibody fragments from combinatorial antibody libraries directed to the U1snRNP associated U1C protein; epitope mapping, immunolocalization and V-gene usage. Mol Immunol. 1998;35:1045-55 pubmed
    ..The two cross-reactive antibodies immunoprecipitate the other Sm containing snRNPs as well. Using confocal immunofluorescence microscopy we could show that the major part of the U1C protein is localized within the coiled body structure. ..
  22. Nagengast A, Stitzinger S, Tseng C, Mount S, Salz H. Sex-lethal splicing autoregulation in vivo: interactions between SEX-LETHAL, the U1 snRNP and U2AF underlie male exon skipping. Development. 2003;130:463-71 pubmed
  23. Yong J, Pellizzoni L, Dreyfuss G. Sequence-specific interaction of U1 snRNA with the SMN complex. EMBO J. 2002;21:1188-96 pubmed
    ..These findings indicate that SMN complex interaction with SL1 is sequence-specific and critical for U1 snRNP biogenesis, further supporting the direct role of the SMN complex in RNP biogenesis. ..
  24. Hof D, Raats J, Pruijn G. Apoptotic modifications affect the autoreactivity of the U1 snRNP autoantigen. Autoimmun Rev. 2005;4:380-8 pubmed
  25. Caputi M, Freund M, Kammler S, Asang C, Schaal H. A bidirectional SF2/ASF- and SRp40-dependent splicing enhancer regulates human immunodeficiency virus type 1 rev, env, vpu, and nef gene expression. J Virol. 2004;78:6517-26 pubmed
    ..4, even when the 5' splice site and the U1 snRNA have been mutated to obtain a perfect complementary match. The ESE characterized here is highly conserved in most viral subtypes. ..
  26. Greidinger E, Hoffman R. The appearance of U1 RNP antibody specificities in sequential autoimmune human antisera follows a characteristic order that implicates the U1-70 kd and B'/B proteins as predominant U1 RNP immunogens. Arthritis Rheum. 2001;44:368-75 pubmed
    ..Orderly patterns of emergence of U1 RNP peptide antibodies appear to exist in humans. Two peptides, 70 kd and B'/B, show characteristics of early immunogens in the development of human RNP immunity. ..
  27. Palfi Z, Schimanski B, GUNZL A, Lücke S, Bindereif A. U1 small nuclear RNP from Trypanosoma brucei: a minimal U1 snRNA with unusual protein components. Nucleic Acids Res. 2005;33:2493-503 pubmed
    ..These data result in a model of the trypanosome U1 snRNP, which deviates substantially from our classical view of the U1 particle and may reflect the special requirements for splicing of a small set of cis-introns in trypanosomes. ..
  28. Will C, Rumpler S, Klein Gunnewiek J, van Venrooij W, Luhrmann R. In vitro reconstitution of mammalian U1 snRNPs active in splicing: the U1-C protein enhances the formation of early (E) spliceosomal complexes. Nucleic Acids Res. 1996;24:4614-23 pubmed
    ..Studies with recombinant U1-C protein mutants indicated that the N-terminal domain of U1-C is necessary and sufficient for the stimulation of E complex formation. ..
  29. Zhu H, Hasman R, Young K, Kedersha N, Lou H. U1 snRNP-dependent function of TIAR in the regulation of alternative RNA processing of the human calcitonin/CGRP pre-mRNA. Mol Cell Biol. 2003;23:5959-71 pubmed
    ..Conversely, TIAR binding promotes U6 snRNA binding to its target. The synergistic relationship between TIAR and U6 snRNA strongly suggests a novel role of U6 snRNP in regulated alternative RNA processing. ..
  30. Zhao Y, Baranger A. Design of an adenosine analogue that selectively improves the affinity of a mutant U1A protein for RNA. J Am Chem Soc. 2003;125:2480-8 pubmed
    ..Experiments with other U1A mutant proteins suggest that the stabilization of the complex between the Phe56Ala U1A protein and stem loop 2 RNA is due to a specific interaction between the Phe56Ala U1A protein and A6-4CPh stem loop 2 RNA. ..
  31. Guan F, Palacios D, Hussein R, Gunderson S. Determinants within an 18-amino-acid U1A autoregulatory domain that uncouple cooperative RNA binding, inhibition of polyadenylation, and homodimerization. Mol Cell Biol. 2003;23:3163-72 pubmed
    ..Our molecular dissection of the consequences of conformational changes within an RNP complex presents a powerful example to those studying more complicated pre-mRNA-regulatory systems. ..
  32. Ramírez Sandoval R, Sánchez Rodriguez S, Herrera van Oostdam D, Avalos Diaz E, Herrera Esparza R. Antinuclear antibodies recognize cellular autoantigens driven by apoptosis. Joint Bone Spine. 2003;70:187-94 pubmed
    ..Apoptotic changes would contribute to break down the tolerance in autoimmune connective tissue disease. ..
  33. Lockhart S, Rymond B. Commitment of yeast pre-mRNA to the splicing pathway requires a novel U1 small nuclear ribonucleoprotein polypeptide, Prp39p. Mol Cell Biol. 1994;14:3623-33 pubmed
    The binding of a U1 small nuclear ribonucleoprotein (snRNP) particle to the 5' splice site region of a pre-mRNA is a primary step of intron recognition...
  34. Buratti E, Baralle M, De Conti L, Baralle D, Romano M, Ayala Y, et al. hnRNP H binding at the 5' splice site correlates with the pathological effect of two intronic mutations in the NF-1 and TSHbeta genes. Nucleic Acids Res. 2004;32:4224-36 pubmed
    ..Depletion analyses shows that this protein restricts the accessibility of U1 small nuclear ribonucleoprotein (U1snRNA) to the donor site...
  35. Kühn Hölsken E, Dybkov O, Sander B, Luhrmann R, Urlaub H. Improved identification of enriched peptide RNA cross-links from ribonucleoprotein particles (RNPs) by mass spectrometry. Nucleic Acids Res. 2007;35:e95 pubmed
    ..Applying our approach to a partial complex of U2 snRNP allowed us to identify the contact site between the U2 snRNP-specific protein p14/SF3b14a and the branch-site interacting region (BSiR) of U2 snRNA. ..
  36. Greidinger E, Foecking M, Ranatunga S, Hoffman R. Apoptotic U1-70 kd is antigenically distinct from the intact form of the U1-70-kd molecule. Arthritis Rheum. 2002;46:1264-9 pubmed
    ..Immunity to apoptotically modified proteins can develop against caspase-cleaved forms or against forms that undergo additional posttranslational modification. ..
  37. Nagengast A, Salz H. The Drosophila U2 snRNP protein U2A' has an essential function that is SNF/U2B" independent. Nucleic Acids Res. 2001;29:3841-7 pubmed
    ..Thus together these data demonstrate that in Drosophila U2A' has an essential function that is unrelated to its role as the partner protein of SNF/U2B". ..
  38. Rupert P, Xiao H, Ferré D Amaré A. U1A RNA-binding domain at 1.8 A resolution. Acta Crystallogr D Biol Crystallogr. 2003;59:1521-4 pubmed
    ..Alternatively, the malonate (several molecules of which are bound in the vicinity of the RNA-binding surface) may mimic RNA. ..
  39. Will C, Luhrmann R. Spliceosomal UsnRNP biogenesis, structure and function. Curr Opin Cell Biol. 2001;13:290-301 pubmed
  40. Malmegrim K, Pruijn G, van Venrooij W. The fate of the U1 snRNP autoantigen during apoptosis: implications for systemic autoimmunity. Isr Med Assoc J. 2002;4:706-12 pubmed
  41. Lorkovic Z, Hilscher J, Barta A. Use of fluorescent protein tags to study nuclear organization of the spliceosomal machinery in transiently transformed living plant cells. Mol Biol Cell. 2004;15:3233-43 pubmed
  42. Hieda M, Tachibana T, Fukumoto M, Yoneda Y. Nuclear import of the U1A splicesome protein is mediated by importin alpha /beta and Ran in living mammalian cells. J Biol Chem. 2001;276:16824-32 pubmed
  43. Akker S, Misra S, Aslam S, Morgan E, Smith P, Khoo B, et al. Pre-spliceosomal binding of U1 small nuclear ribonucleoprotein (RNP) and heterogenous nuclear RNP E1 is associated with suppression of a growth hormone receptor pseudoexon. Mol Endocrinol. 2007;21:2529-40 pubmed
    ..experiments showed that specific binding of heterogenous nuclear ribonucleoprotein E1 (hnRNP E1) and U1 small nuclear ribonucleoprotein (snRNP) in the pre-spliceosomal complex was associated with silencing of pseudoexon splicing...
  44. Kormos B, Baranger A, Beveridge D. A study of collective atomic fluctuations and cooperativity in the U1A-RNA complex based on molecular dynamics simulations. J Struct Biol. 2007;157:500-13 pubmed
    ..This method has significant implications as a predictive tool regarding cooperativity in the protein-nucleic acid recognition process. ..
  45. Pagani F, Buratti E, Stuani C, Bendix R, Dork T, Baralle F. A new type of mutation causes a splicing defect in ATM. Nat Genet. 2002;30:426-9 pubmed
    ..a new intron-splicing processing element (ISPE) complementary to U1 snRNA, the RNA component of the U1 small nuclear ribonucleoprotein (snRNP)...
  46. Ali G, Prasad K, Hanumappa M, Reddy A. Analyses of in vivo interaction and mobility of two spliceosomal proteins using FRAP and BiFC. PLoS ONE. 2008;3:e1953 pubmed publisher
    ..Furthermore, although it appears that U1-70K moves by diffusion its mobility is regulated by phosphorylation and transcription. ..
  47. Labourier E, Adams M, Rio D. Modulation of P-element pre-mRNA splicing by a direct interaction between PSI and U1 snRNP 70K protein. Mol Cell. 2001;8:363-73 pubmed
    ..Here we have identified a direct association of PSI with the spliceosomal U1 small nuclear ribonucleoprotein (snRNP) particle in somatic nuclear extracts...
  48. Urlaub H, Raker V, Kostka S, Luhrmann R. Sm protein-Sm site RNA interactions within the inner ring of the spliceosomal snRNP core structure. EMBO J. 2001;20:187-96 pubmed
    ..Our results thus provide the first evidence that, within the core snRNP, multiple Sm protein-Sm site RNA contacts occur on the inner surface of the heptameric Sm protein ring. ..
  49. Ma J, Gunderson S, Phillips C. Non-snRNP U1A levels decrease during mammalian B-cell differentiation and release the IgM secretory poly(A) site from repression. RNA. 2006;12:122-32 pubmed
  50. Chung S, McLean M, Rymond B. Yeast ortholog of the Drosophila crooked neck protein promotes spliceosome assembly through stable U4/U6.U5 snRNP addition. RNA. 1999;5:1042-54 pubmed
    ..Our results indicate that Clf1p acts as a scaffolding protein in spliceosome assembly and suggest that Clf1p may support the cross-intron bridge during the prespliceosome-to-spliceosome transition. ..
  51. Showalter S, Hall K. A functional role for correlated motion in the N-terminal RNA-binding domain of human U1A protein. J Mol Biol. 2002;322:533-42 pubmed
    ..Interpretation of the novel RED results and corresponding NMR relaxation data suggests that the loss of collective motions in the mutants could account for their weak RNA-binding. ..
  52. Kotovic K, Lockshon D, Boric L, Neugebauer K. Cotranscriptional recruitment of the U1 snRNP to intron-containing genes in yeast. Mol Cell Biol. 2003;23:5768-79 pubmed
    ..Thus, U1 snRNP accumulation at genes correlated with the presence and position of introns, indicating that introns are necessary for cotranscriptional U1 snRNP recruitment and/or retention. ..
  53. Malca H, Shomron N, Ast G. The U1 snRNP base pairs with the 5' splice site within a penta-snRNP complex. Mol Cell Biol. 2003;23:3442-55 pubmed
    ..This fraction is functional in mRNA spliceosome assembly when supplemented with soluble nuclear proteins. The results argue that U1 can bind the 5' splice site in a mammalian preassembled penta-snRNP complex. ..
  54. Wohlwend D, Strasser A, Dickmanns A, Ficner R. Structural basis for RanGTP independent entry of spliceosomal U snRNPs into the nucleus. J Mol Biol. 2007;374:1129-38 pubmed
  55. Urlaub H, Hartmuth K, Kostka S, Grelle G, Luhrmann R. A general approach for identification of RNA-protein cross-linking sites within native human spliceosomal small nuclear ribonucleoproteins (snRNPs). Analysis of RNA-protein contacts in native U1 and U4/U6.U5 snRNPs. J Biol Chem. 2000;275:41458-68 pubmed
    ..In summary, our approach provides a rapid method for identification of RNA-protein contact sites within native snRNP particles as well as other ribonucleoprotein particles. ..
  56. Maroney P, Romfo C, Nilsen T. Functional recognition of 5' splice site by U4/U6.U5 tri-snRNP defines a novel ATP-dependent step in early spliceosome assembly. Mol Cell. 2000;6:317-28 pubmed
    ..We propose that U1 and U5 snRNPs functionally collaborate to recognize and define the 5' splice site prior to establishment of communication with the 3' splice site. ..
  57. Dieker J, Cisterna B, Monneaux F, Decossas M, van der Vlag J, Biggiogera M, et al. Apoptosis-linked changes in the phosphorylation status and subcellular localization of the spliceosomal autoantigen U1-70K. Cell Death Differ. 2008;15:793-804 pubmed publisher
  58. Das R, Yu J, Zhang Z, Gygi M, Krainer A, Gygi S, et al. SR proteins function in coupling RNAP II transcription to pre-mRNA splicing. Mol Cell. 2007;26:867-81 pubmed
    ..Thus, these factors readily out-compete inhibitory hnRNP proteins, resulting in efficient spliceosome assembly on nascent RNAP II transcripts. ..
  59. Pomeranz Krummel D, Oubridge C, Leung A, Li J, Nagai K. Crystal structure of human spliceosomal U1 snRNP at 5.5 A resolution. Nature. 2009;458:475-80 pubmed publisher
    Human spliceosomal U1 small nuclear ribonucleoprotein particles (snRNPs), which consist of U1 small nuclear RNA and ten proteins, recognize the 5' splice site within precursor messenger RNAs and initiate the assembly of the spliceosome ..
  60. Katsamba P, Myszka D, Laird Offringa I. Two functionally distinct steps mediate high affinity binding of U1A protein to U1 hairpin II RNA. J Biol Chem. 2001;276:21476-81 pubmed
    ..Our observations explain the extraordinary affinity of U1A for its target and may suggest a general mechanism for high affinity RNA/protein interactions. ..
  61. Stark H, Dube P, Luhrmann R, Kastner B. Arrangement of RNA and proteins in the spliceosomal U1 small nuclear ribonucleoprotein particle. Nature. 2001;409:539-42 pubmed
  62. Förch P, Puig O, Kedersha N, Martinez C, Granneman S, Seraphin B, et al. The apoptosis-promoting factor TIA-1 is a regulator of alternative pre-mRNA splicing. Mol Cell. 2000;6:1089-98 pubmed
  63. Degen W, Aarssen Y, Pruijn G, Utz P, van Venrooij W. The fate of U1 snRNP during anti-Fas induced apoptosis: specific cleavage of the U1 snRNA molecule. Cell Death Differ. 2000;7:70-9 pubmed
  64. Flickinger T, Salz H. The Drosophila sex determination gene snf encodes a nuclear protein with sequence and functional similarity to the mammalian U1A snRNP protein. Genes Dev. 1994;8:914-25 pubmed
    ..These studies provide the first demonstration, in a multicellular organism, that mutations in a U1 snRNP protein alter splicing in vivo. ..
  65. Nelissen R, Will C, van Venrooij W, Luhrmann R. The association of the U1-specific 70K and C proteins with U1 snRNPs is mediated in part by common U snRNP proteins. EMBO J. 1994;13:4113-25 pubmed
    The U1 small nuclear ribonucleoprotein particle (snRNP)-specific 70K and A proteins are known to bind directly to stem-loops of the U1 snRNA, whereas the U1-C protein does not bind to naked U1 snRNA, but depends on other U1 snRNP protein ..
  66. Fabrizio P, Esser S, Kastner B, Luhrmann R. Isolation of S. cerevisiae snRNPs: comparison of U1 and U4/U6.U5 to their human counterparts. Science. 1994;264:261-5 pubmed
    ..U5 snRNPs are significantly similar. The preparative isolation of yeast snRNPs will allow the cloning as well as genetic and phylogenetic analysis of snRNP proteins which will accelerate our understanding of their function. ..
  67. Rossi F, Forne T, Antoine E, Tazi J, Brunel C, Cathala G. Involvement of U1 small nuclear ribonucleoproteins (snRNP) in 5' splice site-U1 snRNP interaction. J Biol Chem. 1996;271:23985-91 pubmed
    b>U1 small nuclear ribonucleoprotein (snRNP) is an important ribonucleoprotein involved early in the spliceosome formation to commit pre-mRNAs to the splicing pathway...
  68. Puig O, Gottschalk A, Fabrizio P, Seraphin B. Interaction of the U1 snRNP with nonconserved intronic sequences affects 5' splice site selection. Genes Dev. 1999;13:569-80 pubmed
    ..This supports a model where early 5' splice recognition results from a network of interactions established by the splicing machinery with various regions of the pre-mRNA. ..
  69. McCullough A, Berget S. An intronic splicing enhancer binds U1 snRNPs to enhance splicing and select 5' splice sites. Mol Cell Biol. 2000;20:9225-35 pubmed
    ..We suggest that the G-rich region near vertebrate 5' splice sites promotes accurate splice site recognition by recruiting the U1 snRNP. ..
  70. Huber J, Dickmanns A, Luhrmann R. The importin-beta binding domain of snurportin1 is responsible for the Ran- and energy-independent nuclear import of spliceosomal U snRNPs in vitro. J Cell Biol. 2002;156:467-79 pubmed
    ..Our results suggest that the nature of the IBB domain modulates the strength and/or site of interaction of impbeta with nucleoporins of the nuclear pore complex, and thus whether or not Ran is required to dissociate these interactions. ..
  71. Golovkin M, Reddy A. Expression of U1 small nuclear ribonucleoprotein 70K antisense transcript using APETALA3 promoter suppresses the development of sepals and petals. Plant Physiol. 2003;132:1884-91 pubmed
    b>U1 small nuclear ribonucleoprotein (snRNP)-70K (U1-70K), a U1 snRNP-specific protein, is involved in the early stages of spliceosome formation. In non-plant systems, it is involved in constitutive and alternative splicing...
  72. Greidinger E, Foecking M, Magee J, Wilson L, Ranatunga S, Ortmann R, et al. A major B cell epitope present on the apoptotic but not the intact form of the U1-70-kDa ribonucleoprotein autoantigen. J Immunol. 2004;172:709-16 pubmed
    ..Immunization of mice against this epitope induces an immune response with features seen in human anti-70k autoimmune disease. ..
  73. Newo A, Lützelberger M, Bottner C, Wehland J, Wissing J, Jänsch L, et al. Proteomic analysis of the U1 snRNP of Schizosaccharomyces pombe reveals three essential organism-specific proteins. Nucleic Acids Res. 2007;35:1391-401 pubmed
    ..pombe are essential for growth. We will discuss the differences between the U1 snRNPs with respect to the organism-specific proteins found in the two yeasts and the resulting effect it has on pre-mRNA splicing. ..
  74. Cao W, Garcia Blanco M. A serine/arginine-rich domain in the human U1 70k protein is necessary and sufficient for ASF/SF2 binding. J Biol Chem. 1998;273:20629-35 pubmed
    ..ASF/SF2, SC35, and other members of the serine/arginine family, interact with the 70k protein of the U1 small nuclear ribonucleoprotein. The binding of this protein with ASF/SF2 is thought to enhance recognition of the 5' splice site of ..
  75. Gottschalk A, Tang J, Puig O, Salgado J, Neubauer G, Colot H, et al. A comprehensive biochemical and genetic analysis of the yeast U1 snRNP reveals five novel proteins. RNA. 1998;4:374-93 pubmed
    ..Finally, we show that Nam8p/Mud15p contributes to the stability of U1 snRNP. ..
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