Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.3 (RNase T1)
 1,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The in vitro interaction of recombinant hnRNP A1 with purified snRNPs and with pre-mRNAs was investigated. We show that protein A1 can stably bind U2 and U4 snRNP but not U1. Oligo-RNAse H cleavage of U2 nucleotides involved in base pairing with the branch site, totally eliminates the A1-U2 interaction. RNase T1 protection and immunoprecipitation experiments demonstrate that recombinant protein A1 specifically binds the 3'-end regions of both beta-globin and Ad-2 introns. However, while on the beta-globin intron only binding to the polypyrimidine tract was observed, on the Ad-2 intron a 32 nt fragment encompassing the branch point and the AG splice-site dinucleotide was bound and protected. Such protection was drastically reduced in the presence of U2 snRNP. Altogether these results indicate that protein A1 can establish a different pattern of association with different pre-mRNAs and support the hypothesis that this protein could play a role in the annealing of U2 to the branch site and hence in the early events of pre-splicing complex assembly.
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PMID:Interaction of hnRNP A1 with snRNPs and pre-mRNAs: evidence for a possible role of A1 RNA annealing activity in the first steps of spliceosome assembly. 132 35

The binding of hnRNP proteins to pre-mRNAs in nuclear extracts, and as isolated proteins, was studied by using monoclonal antibody immunopurification of hnRNP proteins bound to RNase T1-generated fragments. Several major hnRNP proteins, A1, C and D, bind specifically to the 3' end of introns within a region containing the conserved polypyrimidine stretch between the branch site and the 3' splice site. Mutations which alter the conserved 3' splice site dinucleotide AG strongly impair or abolish the binding of the A1 protein as well as of an anti-Sm reactive component(s) to this region. The A1, C and D proteins do not bind efficiently to fragments of either bacterial RNA or the intronless spliced product (mRNA). The binding of these proteins at the 3' end of the intron does not require addition to the extract of exogenous ATP, but remains after ATP addition. These findings demonstrate that several hnRNP proteins have RNA binding specificities on pre-mRNA, and suggest a model for hnRNP particle structure and assembly.
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PMID:RNA binding specificity of hnRNP proteins: a subset bind to the 3' end of introns. 320 40

The protein content of spermatocyte nuclei from X/Y males and mutants of D. hydei which lack different Y chromosomal loop forming sites, was compared with that of X/0 males in 14C/3H double labelling experiments. Proteins of 45,000, 52,000, 54,000, 66,000, 80,000, 84,000 and 170,000 Dalton are found to be enriched in nuclei containing two or more active Y chromosomal loop forming sites. These proteins are also present in the nuclei of X0 males. In the complete absence of the Y-chromosomal loops proteins of 35,000, 46,000, 58,000 and 110,000 Dalton become enriched in the spermatocyte nuclei. - Analysis of the nuclear RNP of spermatocytes led to the isolation of an hnRNP-containing fraction with an S-value of greater than 900S (RNP-PP), - In the RNP-PP of XY males labelled protein material associated with hnRNA is enriched by a factor of approximately 3 in respect to the X0 genotype. The nuclear RNP has a heterogenous buoyant density in CsCl of rho = 1.33 to 1.43 g/cm3. RNase T1 treatment of the crude nuclear RNP from XY males prior to sucrose gradient analysis shows that the 66,000 Dalton protein which is also strongly enriched in the nuclei in the presence of active Y chromosomal loop forming sites, is the main protein associated with protected RNA-sequences of 80-120- 300 nucleotides in length. Competitive nitrocellulose filter binding assays reveal that the 66,000 Dalton protein predominantly forms in 2 M NaCl stable RNA/protein complexes with the poly A+hnRNA of the RNP-PP. Those RNP complexes have a buoyant density of rho = 1.43 g/cm3 in CsCl. The results are discussed in relation to the nuclear structure and the function of the Y chromosomal loops during spermatogenesis in Drosophila hydei.
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PMID:Analysis of nuclear proteins in primary spermatocytes of Drosophila hydei: The correlation of nuclear proteins with the function of the Y chromosomal loops. 729 52

The hnRNP A1 pre-mRNA is alternatively spliced to yield the A1 and A1b mRNAs, which encode proteins differing in their ability to modulate 5' splice site selection. Sequencing a genomic portion of the murine A1 gene revealed that the intron separating exon 7 and the alternative exon 7B is highly conserved between mouse and human. In vitro splicing assays indicate that a conserved element (CE1) from the central portion of the intron shifts selection toward the distal donor site when positioned in between the 5' splice sites of exon 7 and 7B. In vivo, the CE1 element promotes exon 7B skipping. A 17-nucleotide sequence within CE1 (CE1a) is sufficient to activate the distal 5' splice site. RNase T1 protection/immunoprecipitation assays indicate that hnRNP A1 binds to CE1a, which contains the sequence UAGAGU, a close match to the reported optimal A1 binding site, UAGGGU. Replacing CE1a by different oligonucleotides carrying the sequence UAGAGU or UAGGGU maintains the preference for the distal 5' splice site. In contrast, mutations in the AUGAGU sequence activate the proximal 5' splice site. In support of a direct role of the A1-CE1 interaction in 5'-splice-site selection, we observed that the amplitude of the shift correlates with the efficiency of A1 binding. Whereas addition of SR proteins abrogates the effect of CE1, the presence of CE1 does not modify U1 snRNP binding to competing 5' splice sites, as judged by oligonucleotide-targeted RNase H protection assays. Our results suggest that hnRNP A1 modulates splice site selection on its own pre-mRNA without changing the binding of U1 snRNP to competing 5' splice sites.
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PMID:An intron element modulating 5' splice site selection in the hnRNP A1 pre-mRNA interacts with hnRNP A1. 912 25

Recent work identified an RNA binding protein whose presence in brain tumors correlated with translational repression of Glut1 expression. RNase T1 mapping demonstrated that this protein bound an AU-rich response element (AURE) in the Glut1 3'UTR. Facilitated by its differential expression in brain tumor cytosols, we identified this Glut1 RNA binding protein as hnRNP A2. Studies further demonstrated that hnRNP A2 was the major Glut1 RNA binding activity in other cell lines. Recombinant hnRNP A2 exhibited equivalent Glut1 RNA binding specificity, quite distinct from the related AURE binding protein hnRNP A1. These data indicate that hnRNP A2 is the Glut1 AURE binding protein whose cytoplasmic expression in gliomas is associated with translational repression and mRNA instability. Using this approach, we also identified the other major Glut1 3'UTR RNA binding activity as hnRNP L. Stimuli (hypoxia and hypoglycemia) which increase Glut1 mRNA stability selectively decreased polysomal levels of hnRNP A2 and L. Immunoprecipitation demonstrated that hnRNP A2 and L exist as a complex in vivo. As a result of these and other studies, we conclude that hnRNP A2 and L associate in vivo and independently bind the 3'UTR of Glut1 mRNA.
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PMID:hnRNP A2 and hnRNP L bind the 3'UTR of glucose transporter 1 mRNA and exist as a complex in vivo. 1044 80