Affinage

SNRPA

U1 small nuclear ribonucleoprotein A · UniProt P09012

Length
282 aa
Mass
31.3 kDa
Annotated
2026-06-10
100 papers in source corpus 32 papers cited in narrative 29 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

SNRPA (U1A) is an RRM-containing RNA-binding protein that functions both as a core component of the U1 snRNP and as a sequence-specific regulator of 3'-end processing and alternative splicing (PMID:2531658, PMID:8458082, PMID:8262062). Its N-terminal RRM recognizes the AUUGCAC loop of U1 snRNA hairpin II through conserved RNP1 and RNP2 motifs that contact the RNA via base stacking with aromatic side chains and hydrogen-bond networks (PMID:7984237, PMID:1833186), with binding specificity over the U2B''/U2 snRNA pair dictated by a small set of protein and RNA residues (PMID:2140872, PMID:9814759). Recognition proceeds by a two-step 'lure and lock' mechanism: rapid electrostatic association followed by a locking step in which the C-terminal helix C, which occludes the binding surface in the free protein, rotates onto the RNA to stabilize the complex through stacking and intraprotein hydrogen bonds (PMID:8609632, PMID:11297556, PMID:23703211). When U1A is in excess over U1 snRNA, free protein autoregulates its own expression by cooperatively binding two sites in the 3'UTR PIE element of its own pre-mRNA and directly contacting the C-terminus of poly(A) polymerase to inhibit polyadenylation; both cooperativity and PAP inhibition depend on helix C-mediated dimerization, coupling RNA binding to inhibition (PMID:8458082, PMID:8262062, PMID:8313473, PMID:9087430, PMID:10742179, PMID:10688667). This regulatory activity extends to other transcripts, where U1A binds 3'UTR elements to inhibit cleavage and polyadenylation of the IgM secretory poly(A) site by displacing CstF and of SMN pre-mRNA by blocking CPSF cleavage (PMID:15226420, PMID:24362020). A snRNP-free pool of U1A (SF-A) assembles with PSF and p54nrb/p68 to promote pre-mRNA cleavage during polyadenylation (PMID:16373496, PMID:9848648), and U1A also interacts with SAM68 to promote U1 snRNP recruitment to 5' splice sites (PMID:30767021) and controls alternative splicing of ERCC1 exon 8 to support ERCC1-XPF complex formation and DNA damage repair (PMID:39555714). Nuclear import of U1A is mediated by importin alpha/beta and Ran, and the protein shuttles between nucleus and cytoplasm with its distribution set by the number of available RNA binding sites (PMID:1618898, PMID:11278401).

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 1989 High

    Establishing that U1A recognizes a defined RNA element via a discrete RNP motif converted U1A from a snRNP subunit into a tractable sequence-specific RNA-binding protein.

    Evidence in vitro RNA binding, point mutagenesis and deletion analysis mapping the U1 snRNA hairpin II site and the RNP motif

    PMID:2531658

    Open questions at the time
    • No atomic-resolution description of contacts
    • Functional consequence of binding beyond snRNP assembly not addressed
  2. 1990 High

    Defining the few protein and RNA residues that distinguish U1A/U1 from U2B''/U2 explained how closely related RRM proteins achieve target specificity and showed U1A binds independently of accessory proteins.

    Evidence reciprocal specificity-swap experiments with chimeric proteins and RNAs

    PMID:2140872

    Open questions at the time
    • Single critical specificity residue not yet resolved
    • Structural basis of discrimination not shown
  3. 1994 High

    High-resolution structures of the U1A RRM-hairpin II complex and of the free RBD revealed the atomic contacts and the helix C conformational switch underlying recognition.

    Evidence X-ray crystallography at 1.92 Å and multidimensional heteronuclear NMR of the free and bound RBD

    PMID:7984237 PMID:8609632

    Open questions at the time
    • Kinetic ordering of association vs locking not yet defined
    • Behavior of the second RRM (RBD2) unresolved
  4. 1994 High

    Identifying U1A autoregulation through PIE-element binding and direct PAP inhibition established a non-snRNP function and a feedback loop controlling U1A levels.

    Evidence in vitro/in vivo polyadenylation assays, overexpression, domain mutagenesis, and direct U1A-PAP binding

    PMID:8262062 PMID:8313473 PMID:8458082

    Open questions at the time
    • Why two U1A molecules are required not yet structurally explained
    • Whether other mRNAs are similarly regulated unknown at this stage
  5. 1997 High

    Mapping the PAP C-terminal 20 residues and U1A residues 103-119 as the inhibitory interface, and showing two bound U1A molecules are needed, mechanistically linked cooperative RNA binding to polyadenylation control.

    Evidence in vitro PAP inhibition assays, yeast PAP chimera, GST pulldown, splicing/polyadenylation uncoupling

    PMID:9087430

    Open questions at the time
    • Structural basis of the dimer-PAP contact not yet visualized
    • In vivo relevance across cell types not established
  6. 2000 High

    NMR structures of the two-U1A:PIE complex and dimerization mapping showed that helix C drives both RNA-binding cooperativity and ensures PAP inhibition occurs only when U1A is RNA-bound.

    Evidence NMR structure of the 38 kDa trimolecular complex; yeast two-hybrid, coselection, EMSA and polyadenylation assays with dimerization mutants

    PMID:10688667 PMID:10742179

    Open questions at the time
    • Dynamics of dimer assembly in cells not measured
    • Regulation of free vs snRNP-bound U1A partitioning unresolved
  7. 2001 High

    Dissecting binding into an electrostatic 'lure' and a hydrogen-bond/stacking 'lock' step provided a kinetic framework for how the RRM achieves both speed and stability.

    Evidence surface plasmon resonance kinetics with protein and RNA mutants and salt-dependence experiments

    PMID:11297556

    Open questions at the time
    • Single mutants only partially separate the steps
    • Generalizability to other RRM-RNA pairs not tested here
  8. 2001 High

    Defining importin alpha/beta- and Ran-dependent nuclear import and an internal NLS clarified how U1A localizes, complementing earlier work showing distribution follows available RNA binding sites.

    Evidence microinjection of deletion mutants, in vitro import assays with recombinant importins, and in vivo Ran inhibition; earlier Xenopus oocyte and RNA-competition assays

    PMID:11278401 PMID:1618898

    Open questions at the time
    • Regulation of shuttling under physiological conditions unclear
    • Cytoplasmic functions of shuttling U1A not defined
  9. 2006 High

    Purification of the snRNP-free SF-A complex containing PSF and p54nrb/p68, and its requirement for pre-mRNA cleavage, distinguished a positive 3'-processing role for non-snRNP U1A from its inhibitory autoregulatory role.

    Evidence TAP purification with MS, immunodepletion/reconstitution of in vitro polyadenylation, Co-IP; earlier sucrose gradient and conformation-specific antibody work

    PMID:16373496 PMID:9404895 PMID:9848648

    Open questions at the time
    • How U1A partitions between SF-A and inhibitory pools not established
    • Substrate selectivity of SF-A-promoted cleavage unknown
  10. 2006 Medium

    Linking declining non-snRNP U1A to release of the IgM secretory poly(A) site during B-cell differentiation gave a physiological setting for U1A-mediated cleavage inhibition through CstF displacement.

    Evidence flow cytometry, exhaustive immunoprecipitation, competitor-RNA de-repression and PAP inhibition assays; earlier mapping of AUGCN motifs and CstF inhibition

    PMID:15226420 PMID:16373497

    Open questions at the time
    • Single lab; in vivo causality during differentiation not genetically proven
    • Breadth of poly(A) sites regulated this way unknown
  11. 2013 High

    Demonstrating direct U1A binding to the SMN 3'UTR with CPSF-specific cleavage inhibition and reduced SMN protein extended U1A's regulatory reach to a disease-relevant transcript.

    Evidence in vitro RNA binding and cleavage assays plus overexpression with SMN protein readout

    PMID:24362020

    Open questions at the time
    • Physiological conditions favoring this inhibition not defined
    • Endogenous regulation of SMN by U1A in neurons not shown
  12. 2019 High

    Identifying a SAM68-U1A interaction that promotes U1 snRNP recruitment to a 5' splice site showed U1A participates in splice-site selection and intron retention/premature polyadenylation control.

    Evidence Co-IP, domain-deletion mapping, splicing and polyadenylation assays on mTor intron 5

    PMID:30767021

    Open questions at the time
    • Genome-wide scope of SAM68-U1A-regulated targets unknown
    • Mechanism of snRNP recruitment beyond the contact not detailed
  13. 2024 Medium

    Showing SNRPA controls ERCC1 exon 8 splicing to support ERCC1-XPF complex formation and DNA repair, with its own mRNA regulated by m6A reader IGF2BP1 and stabilizer ELAVL1, connected U1A to a cancer-relevant splicing and drug-resistance axis.

    Evidence CRISPR knockout/shRNA, splicing assays, Co-IP for ERCC1-XPF, and mouse xenograft

    PMID:39555714

    Open questions at the time
    • Single lab; direct mechanism of exon 8 recognition not mapped
    • Generality of U1A-regulated alternative splicing not established

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the cell dynamically partitions U1A among the U1 snRNP, SF-A, and free inhibitory pools to coordinate splicing and 3'-end processing genome-wide remains unresolved.
  • No quantitative model of pool partitioning in vivo
  • Transcriptome-wide map of direct U1A regulatory targets incomplete
  • Signals controlling free vs snRNP-bound U1A levels unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 8 GO:0098772 molecular function regulator activity 4 GO:0140110 transcription regulator activity 3
Localization
GO:0005634 nucleus 2 GO:0005829 cytosol 1
Pathway
R-HSA-8953854 Metabolism of RNA 4 R-HSA-74160 Gene expression (Transcription) 3
Partners
ELAVL1ERCC1IGF2BP1NONOPAPOLAPSF/SFPQSAM68/KHDRBS1
Complex memberships
SF-A (U1A-PSF-p54nrb-p68)U1 snRNP

Evidence

Reading pass · 29 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1994 Crystal structure of the N-terminal RNA-binding domain of U1A complexed with a 21-nucleotide RNA hairpin (hairpin II of U1 snRNA) at 1.92 Å resolution revealed that the 10-nucleotide RNA loop binds to the surface of the beta-sheet as an open structure, with the AUUGCAC sequence interacting extensively with conserved RNP1 and RNP2 motifs and the C-terminal extension via base stacking with aromatic side chains and direct/water-mediated hydrogen bonds. X-ray crystallography at 1.92 Å resolution Nature High 7984237
1989 The RNA binding site for U1A on U1 snRNA is hairpin II (positions 48-91), with the conserved loop sequence critical for interaction. The region of U1A required for RNA binding consists of an ~80 amino acid RNP motif plus flanking residues; point mutations in the most conserved RNP1 and RNP2 regions abolish RNA binding. In vitro RNA binding assays, point mutagenesis, deletion analysis The EMBO journal High 2531658
1990 Binding specificity between U1A/U1 snRNA and U2B''/U2 snRNA pairs is determined by two nucleotides in the RNA and eight amino acids in the protein; exchange of these residues reverses specificity. U1A binds U1 snRNA independently, whereas U2B'' requires accessory protein U2A' for specific binding to U2 snRNA. In vitro RNA binding assays with chimeric protein and RNA mutants Nature High 2140872
1991 Molecular contacts between U1A protein and U1 snRNA identified by mutagenesis: Thr11→Val and Asn15→Val in RNP2 abolished binding; Tyr13→Phe and Asn16→Val substantially reduced binding. Arg52 in RNP1 forms a salt bridge with RNA phosphates. Ethylation protection showed phosphates of the 3' two-thirds of loop II and the 5' stem contact U1A. A→G and G→A replacements in loop II substantially reduced binding. Site-directed mutagenesis combined with filter binding and ethylation protection of U1 RNA The EMBO journal High 1833186
1993 U1A protein autoregulates its own mRNA production by binding two sites in the conserved 47 nt region of the 3' UTR of its own pre-mRNA, inhibiting polyadenylation. Overexpression of U1A in mouse cells downregulates endogenous U1A mRNA; a single U1A molecule binding is insufficient for efficient polyadenylation inhibition. In vitro binding assays, in vivo overexpression, in vitro polyadenylation assays, structure probing, mutational analysis of pre-mRNA Cell / The EMBO journal High 8262062 8458082
1994 U1A protein bound to its own pre-mRNA directly interacts with mammalian poly(A) polymerase (PAP) and inhibits both specific and nonspecific polyadenylation. This inhibition does not prevent CPSF binding or pre-mRNA cleavage. Domains in both U1A (identified by mutagenesis) and the C-terminus of PAP are required; the interaction is specific to mammalian (not yeast) PAP. In vitro polyadenylation assays, domain mutagenesis, in vitro protein-protein interaction (direct binding of U1A to PAP) Cell High 8313473
1992 U1A nuclear localization requires an active transport process independent of U1 snRNA binding; the nuclear localization signal is an unusually large sequence element between amino acids 94 and 204. U1A shuttles between nucleus and cytoplasm, and its intracellular distribution is determined by the number of free RNA binding sites available in each compartment. Microinjection of deletion mutants into Xenopus oocytes, transfection assays, introduction of competing RNA sequences The Journal of cell biology High 1618898
1996 The solution NMR structure of U1A N-terminal RBD (residues 2-117) shows that the C-terminal helix C lies across the beta-sheet in the free protein (acting as a 'lid'), making hydrophobic contacts that stabilize the protein. Upon RNA binding, helix C rotates ~135° to allow Tyr13, Phe56 and Gln54 to stack with RNA bases, stabilized in the new position by hydrophobic interactions and a Ser91-Thr11 hydrogen bond. Multi-dimensional heteronuclear NMR solution structure determination with functional validation Journal of molecular biology High 8609632
1997 The carboxy-terminal 20 amino acids of vertebrate PAP are essential for its inhibition by the U1A-RNA complex; transfer of these 20 residues to yeast PAP confers U1A-mediated inhibition. A GST fusion of these PAP residues interacts in vitro with an RNA-U1A complex containing two U1A molecules but not one, explaining the requirement for two U1A-binding sites. U1A amino acids 103-119 are required for PAP inhibition; a multimeric U1A peptide spanning this region uncouples splicing and 3'-end formation in vitro. In vitro PAP inhibition assays with domain mutants, yeast PAP chimera experiments, GST pulldown, in vitro splicing/polyadenylation uncoupling assay Genes & development High 9087430
1997 The NMR structure of the U1A RBD1-polyadenylation inhibitory element (PIE RNA) complex at 1.08 Å interface precision shows that the same heptanucleotide AUUGCAC is recognized in two different structural contexts (hairpin and internal loop) by identical protein contacts; a protein dimer forms via C-terminal contacts that are RNA binding-dependent, providing the structural basis for cooperativity and PAP inhibition. NMR structure determination of U1A-3'UTR complex, model-building based on crystal structure of hairpin complex Structure / Journal of biomolecular NMR High 8736559 9566313
2000 NMR structure of the 38 kDa complex of two U1A proteins bound to PIE RNA shows that cooperativity of U1A binding depends on helix C, which undergoes a conformational change upon RNA binding. This same helix C is adjacent to the PAP-interacting domain, ensuring that PAP inhibition can only occur when U1A is RNA-bound, linking cooperative RNA binding to PAP inhibition. NMR structure determination of trimolecular 38 kDa complex Nature structural biology High 10742179
2000 U1A homodimerizes via two separate regions in the N-terminal 115 residues (one at aa 103-115) even when RNA binding is abolished. Mutation of the aa 103-115 dimerization region abolishes cooperative binding of two U1A molecules to PIE RNA and inhibition of polyadenylation, but does not affect single-molecule binding to PIE RNA. Yeast two-hybrid, in vitro coselection, gel mobility shift, polyadenylation inhibition assays with point and deletion mutants Molecular and cellular biology High 10688667
2001 The nuclear import of U1A is mediated by importin alpha/beta and Ran; the NLS is located within residues 100-144. U1A was shown to bind the C-terminal portion of importin alpha. Nuclear accumulation in intact cells is Ran-dependent and inhibited by the importin beta-binding domain of importin alpha. Microinjection of deletion mutants into BHK21 cells, in vitro nuclear import assay with recombinant importins, in vivo Ran inhibition The Journal of biological chemistry High 11278401
2004 U1A binds two AUGCN(1-3)C motifs within a 29-nucleotide sequence between the two downstream GU-rich regions of the IgM heavy-chain secretory poly(A) site, inhibits binding of CstF 64K to GU-rich elements, and inhibits cleavage at the secretory poly(A) site. In vitro RNA binding assays, polyadenylation cleavage assays, competition binding experiments Molecular and cellular biology High 15226420
2006 A snRNP-free form of U1A (SF-A) exists in human cells as part of a novel complex containing PSF, p54nrb, and p68; this complex promotes pre-mRNA cleavage during polyadenylation. p54nrb is specifically critical for the cleavage function, as shown by immunodepletion/reconstitution experiments. Tandem affinity purification, mass spectrometry, immunodepletion/reconstitution of in vitro polyadenylation, Co-IP RNA High 16373496
1997 Identification of a novel snRNP-free U1A complex (SF-A) in which U1A is not associated with U1 snRNA or other snRNP components, but co-sediments and co-immunoprecipitates with non-snRNP proteins of ~58, 59, 63, 65, and 105 kDa. Anti-SF-A antibodies significantly diminish polyadenylation in vitro, indicating a functional role in this process. Sucrose density gradient fractionation, immunoprecipitation with conformation-specific monoclonal antibody (MAb 12E12), in vitro polyadenylation RNA Medium 9404895
1998 The largest component of the SF-A complex, p105, is PSF (polypyrimidine-tract binding protein-associated splicing factor). PSF co-purifies and co-immunoprecipitates with SF-A from 293T cell nucleoplasm and interacts with SF-A in vitro. Anti-SF-A antibodies inhibit both splicing and polyadenylation in a coupled in vitro reaction. Co-immunoprecipitation, in vitro binding assay, in vitro coupled splicing/polyadenylation assay RNA Medium 9848648
2013 U1A binds directly and with high affinity and specificity to the SMN 3'-UTR adjacent to the polyadenylation site, independent of U1 snRNP. This binding inhibits polyadenylation of SMN pre-mRNA by specifically inhibiting 3' cleavage by CPSF. Excess U1A over U1 snRNA causes inhibition of SMN polyadenylation and decreases SMN protein levels. In vitro RNA binding assays, in vitro polyadenylation/cleavage assays, overexpression experiments with SMN protein level readout The Journal of biological chemistry High 24362020
2007 A conserved U1 site in the U1A gene 3'UTR acts in synergy with PIE to inhibit U1A expression via nuclear polyadenylation inhibition (poly(A) tail addition). The two elements function as a bipartite repressor: the U1 site is normally suppressed by a base-pairing mechanism, but together they form a ternary complex that inhibits polyadenylation without simply stabilizing factor binding. In vitro and in vivo reporter assays, mutational analysis of 3'UTR, in vitro polyadenylation assays RNA Medium 17942741
2019 SAM68 directly interacts with U1A through SAM68's C-terminal tyrosine-rich (YY) domain binding the RRM1 domain of U1A; this interaction promotes U1 snRNP recruitment to the 5' splice site of mTor intron 5. Deletion of the U1A-SAM68 interaction domain or mutation of SAM68-binding sites in mTor intron 5 abrogates U1A recruitment and leads to premature intron 5 termination and polyadenylation. Co-immunoprecipitation, deletion mutagenesis, splicing assays, polyadenylation assays, in vivo and in vitro binding Nucleic acids research High 30767021
2006 Non-snRNP U1A levels decrease during B-cell differentiation, releasing the IgM secretory poly(A) site from repression. Undifferentiated B cells have more total U1A and a greater proportion is non-snRNP-associated, which directly inhibits poly(A) addition. The inhibitory effect is proportional to the amount of available U1A recovered by immunopurification. Flow cytometry, exhaustive immunoprecipitation, cold competitor RNA oligo de-repression of polyadenylation in nuclear extracts, in vitro poly(A) polymerase inhibition assay RNA Medium 16373497
2001 U1A-RNA complex formation involves two mechanistically distinct steps: an initial rapid association driven by electrostatic interactions (slowed by charge neutralization or high salt) and a subsequent 'locking' step driven by close-range hydrogen bonding and stacking interactions (reflected in dissociation rate). Single amino acid substitutions can selectively perturb either step. Surface plasmon resonance (real-time biomolecular interaction analysis) with U1A mutants and RNA mutants, salt dependence experiments The Journal of biological chemistry High 11297556
1995 In vitro phage-display selection identified Leu-49 as a critical residue that disproportionately affects the rates of binding and release of U1A from U1 RNA; it appears to lock the protein onto the RNA. Three other residues in the mutagenized region also proved important for specific RNA binding. Phage-display combinatorial library with affinity selection (in vitro genetic selection), RNA binding assays Proceedings of the National Academy of Sciences of the United States of America Medium 8524863
1997 The NMR structure of U1A C-terminal RNA-binding domain (RBD2) shows it folds as a canonical alpha/beta sandwich but does not bind U1, U2, or U5 snRNA, RNA hairpins, or random sequence RNAs. The two RBDs of the full-length protein exhibit uncorrelated motion due to a highly flexible linker region. NMR structure determination, RNA binding assays with multiple RNA substrates, fluorescence polarization Journal of molecular biology / Biochemistry / Protein science High 7723028 9265619
1998 A single leucine residue in U1A (Leu-44) is critical for the intrinsic specificity of U1A for the U1hpII loop sequence over U2hpIV. U2A' protein enables U2B'' to discriminate loop sequences but not stem sequences; U2A' can also promote heterospecific U1A binding to U2hpIV but requires ~500-fold higher concentration due to preferential U2A' binding to U2B''. In vitro RNA binding assays with chimeric proteins, competition assays, site-directed mutagenesis RNA Medium 9814759
2006 Positively charged residues close to the RNA-binding site (Lys20, Lys22, Lys23) play distinct roles: Lys20 predominantly aids association while Lys22 and Lys23 are important for complex stability. Residues away from the binding site (Arg7, Lys60, Arg70) have minimal effect on either association or stability, demonstrating position-dependent roles of electrostatic interactions in the 'lure and lock' binding model. Surface plasmon resonance kinetics, salt dependence experiments, molecular dynamics simulation Nucleic acids research Medium 16407334
2013 The C-terminal helix (helix C) of U1A RRM1 occludes the RNA-binding surface in the free protein. Truncation or disruption of helix C increases the association rate (by exposing the binding surface) but simultaneously reduces complex stability (loss of locking). The quadruple stacking interaction (involving helix C residues) makes a minor kinetic contribution compared to the intraprotein hydrogen bonds formed when helix C relocates. Surface plasmon resonance kinetics with truncation and point mutants of helix C Nucleic acids research Medium 23703211
2020 SNRPA binds directly to the G-quadruplex structure within the 5'UTR of BAG-1 mRNA. Label-free RNA pulldown from colorectal cancer cell protein extracts followed by LC-MS/MS identified SNRPA; direct binding was confirmed, and knockdown experiments suggested SNRPA modulates BAG-1 expression levels. RNA G-quadruplex pulldown with mutant control, LC-MS/MS, confirmation of direct binding, siRNA knockdown Biochimie Medium 32629040
2024 SNRPA controls alternative splicing of ERCC1 exon 8; its depletion causes ERCC1 exon 8 skipping and reduced ERCC1-XPF complex formation, reducing DNA damage repair. IGF2BP1 (m6A reader) and ELAVL1 (RNA stabilizer) bind SNRPA mRNA, with ELAVL1 promoting SNRPA expression and thereby cisplatin resistance in an SNRPA-dependent manner. CRISPR/Cas9 knockout and shRNA knockdown, overexpression, splicing assays, Co-IP for ERCC1-XPF complex, gene ontology analysis, mouse xenograft model Advanced science Medium 39555714

Source papers

Stage 0 corpus · 100 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1994 Crystal structure at 1.92 A resolution of the RNA-binding domain of the U1A spliceosomal protein complexed with an RNA hairpin. Nature 806 7984237
1989 Identification of the RNA binding segment of human U1 A protein and definition of its binding site on U1 snRNA. The EMBO journal 302 2531658
1990 Major determinants of the specificity of interaction between small nuclear ribonucleoproteins U1A and U2B'' and their cognate RNAs. Nature 262 2140872
1993 The human U1 snRNP-specific U1A protein inhibits polyadenylation of its own pre-mRNA. Cell 197 8458082
1994 The human U1A snRNP protein regulates polyadenylation via a direct interaction with poly(A) polymerase. Cell 193 8313473
1991 Identification of molecular contacts between the U1 A small nuclear ribonucleoprotein and U1 RNA. The EMBO journal 178 1833186
1996 Solution structure of the N-terminal RNP domain of U1A protein: the role of C-terminal residues in structure stability and RNA binding. Journal of molecular biology 161 8609632
1997 Structural basis of the RNA-binding specificity of human U1A protein. The EMBO journal 146 9312034
1980 Nucleotide sequences of nuclear U1A RNAs from chicken, rat and man. Nucleic acids research 139 6159587
2000 Crystallization and structure determination of a hepatitis delta virus ribozyme: use of the RNA-binding protein U1A as a crystallization module. Journal of molecular biology 134 10623545
1992 Intracellular distribution of the U1A protein depends on active transport and nuclear binding to U1 snRNA. The Journal of cell biology 123 1618898
1999 An inhibitor of nuclear export activates the p53 response and induces the localization of HDM2 and p53 to U1A-positive nuclear bodies associated with the PODs. Experimental cell research 122 10222137
2000 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. Nature structural biology 121 10742179
1992 Interaction of N-terminal domain of U1A protein with an RNA stem/loop. Nucleic acids research 115 1508720
1994 Interaction of RNA hairpins with the human U1A N-terminal RNA binding domain. Biochemistry 114 7520277
1997 Involvement of the carboxyl terminus of vertebrate poly(A) polymerase in U1A autoregulation and in the coupling of splicing and polyadenylation. Genes & development 113 9087430
1993 A complex secondary structure in U1A pre-mRNA that binds two molecules of U1A protein is required for regulation of polyadenylation. The EMBO journal 111 8262062
1994 The Drosophila sex determination gene snf encodes a nuclear protein with sequence and functional similarity to the mammalian U1A snRNP protein. Genes & development 88 7926776
1981 The conformation of chicken, rat and human U1A RNAs in solution. Nucleic acids research 86 6164982
2005 Mechanism of Lys48-linked polyubiquitin chain recognition by the Mud1 UBA domain. The EMBO journal 82 16138082
1994 NMR studies of U1 snRNA recognition by the N-terminal RNP domain of the human U1A protein. The EMBO journal 71 8070414
1999 Changes in side-chain and backbone dynamics identify determinants of specificity in RNA recognition by human U1A protein. Journal of molecular biology 69 10588900
2006 The role of positively charged amino acids and electrostatic interactions in the complex of U1A protein and U1 hairpin II RNA. Nucleic acids research 68 16407334
1996 Structure of the polyadenylation regulatory element of the human U1A pre-mRNA 3'-untranslated region and interaction with the U1A protein. Biochemistry 67 8652566
2001 Two functionally distinct steps mediate high affinity binding of U1A protein to U1 hairpin II RNA. The Journal of biological chemistry 66 11297556
1984 Regulation of the trimethylamine N-oxide (TMAO) reductase in Escherichia coli: analysis of tor::Mud1 operon fusion. Molecular & general genetics : MGG 61 6387391
2000 Investigating the binding specificity of U1A-RNA by computational mutagenesis. Journal of molecular biology 60 10623503
1999 RNA recognition by the human U1A protein is mediated by a network of local cooperative interactions that create the optimal binding surface. Journal of molecular biology 59 9878401
1995 Solution structure of the ribosome-binding domain of E. coli translation initiation factor IF3. Homology with the U1A protein of the eukaryotic spliceosome. Journal of molecular biology 59 7490747
1995 Analysis of RNA-binding proteins by in vitro genetic selection: identification of an amino acid residue important for locking U1A onto its RNA target. Proceedings of the National Academy of Sciences of the United States of America 59 8524863
1995 An RBD that does not bind RNA: NMR secondary structure determination and biochemical properties of the C-terminal RNA binding domain from the human U1A protein. Journal of molecular biology 57 7723028
2005 13C NMR relaxation studies of RNA base and ribose nuclei reveal a complex pattern of motions in the RNA binding site for human U1A protein. Journal of molecular biology 55 15890361
2001 Molecular dynamics and thermodynamics of protein-RNA interactions: mutation of a conserved aromatic residue modifies stacking interactions and structural adaptation in the U1A-stem loop 2 RNA complex. Journal of the American Chemical Society 52 11456923
2018 SNRPA enhances tumour cell growth in gastric cancer through modulating NGF expression. Cell proliferation 50 30039889
2010 Induced fit or conformational selection for RNA/U1A folding. RNA (New York, N.Y.) 49 20354153
2006 Do collective atomic fluctuations account for cooperative effects? Molecular dynamics studies of the U1A-RNA complex. Journal of the American Chemical Society 49 16834346
1999 Molecular dynamics simulations of the complex between human U1A protein and hairpin II of U1 small nuclear RNA and of free RNA in solution. Biophysical journal 49 10465742
1996 Drosophila SNF/D25 combines the functions of the two snRNP proteins U1A and U2B' that are encoded separately in human, potato, and yeast. RNA (New York, N.Y.) 49 8846293
1995 Crosslinking of an iodo-uridine-RNA hairpin to a single site on the human U1A N-terminal RNA binding domain. RNA (New York, N.Y.) 48 7489489
1981 General method, using Mu-Mud1 dilysogens, to determine the direction of transcription of and generate deletions in the glnA region of Escherichia coli. Journal of bacteriology 48 6111550
1998 RNA binding mediates the local cooperativity between the beta-sheet and the C-terminal tail of the human U1A RBD1 protein. Journal of molecular biology 46 9466924
1996 RNA hairpins with non-nucleotide spacers bind efficiently to the human U1A protein. Journal of molecular biology 46 8609622
2002 Investigation of a conserved stacking interaction in target site recognition by the U1A protein. Nucleic acids research 44 11788718
1991 Conserved amino acid residues within and outside of the N-terminal ribonucleoprotein motif of U1A small nuclear ribonucleoprotein involved in U1 RNA binding. Journal of molecular biology 44 1829114
2006 p54nrb is a component of the snRNP-free U1A (SF-A) complex that promotes pre-mRNA cleavage during polyadenylation. RNA (New York, N.Y.) 43 16373496
2004 U1A inhibits cleavage at the immunoglobulin M heavy-chain secretory poly(A) site by binding between the two downstream GU-rich regions. Molecular and cellular biology 43 15226420
1995 Molecular characterization of the spliceosomal proteins U1A and U2B" from higher plants. The EMBO journal 43 7556097
1995 Crystallisation of RNA-protein complexes. II. The application of protein engineering for crystallisation of the U1A protein-RNA complex. Journal of molecular biology 41 7783201
2010 Use of the spliceosomal protein U1A to facilitate crystallization and structure determination of complex RNAs. Methods (San Diego, Calif.) 40 20554048
2002 Molecular dynamics simulation studies of induced fit and conformational capture in U1A-RNA binding: do molecular substates code for specificity? Biopolymers 40 12434430
1999 Molecular dynamics studies of U1A-RNA complexes. RNA (New York, N.Y.) 39 10024175
1998 The snRNP-free U1A (SF-A) complex(es): identification of the largest subunit as PSF, the polypyrimidine-tract binding protein-associated splicing factor. RNA (New York, N.Y.) 39 9848648
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