scholarly journals The natural 5' splice site of simian virus 40 large T antigen can be improved by increasing the base complementarity to U1 RNA.

1987 ◽  
Vol 7 (8) ◽  
pp. 3018-3020 ◽  
Author(s):  
Y Zhuang ◽  
H Leung ◽  
A M Weiner
Keyword(s):  
Splice Site ◽  
Consensus Sequence ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen ◽  
Splice Sites ◽  
Small Nuclear Ribonucleoprotein ◽  
Antigen 5

The use of alternative 5' splice sites in the simian virus 40 early-transcription unit controls the ratio of large T to small t antigen during viral infection. To study the regulation of these alternative 5' splice sites, we made two mutants which improve the match of the large-T-antigen 5' splice site to the 5' splice site consensus sequence. Whether these mutants were assayed in vitro or in vivo, we found that the efficiency of large-T splicing is increased by improving the match of the large-T-antigen 5' splice site to the consensus. We conclude that the match of a 5' splice site is an important determinant of 5' splice site utilization and that the simian virus 40 large-T-antigen 5' splice site is almost certainly recognized by the U1 small nuclear RNA component of the U1 small nuclear ribonucleoprotein particle.

The natural 5' splice site of simian virus 40 large T antigen can be improved by increasing the base complementarity to U1 RNA

1987 ◽  
Vol 7 (8) ◽  
pp. 3018-3020
Author(s):  
Y Zhuang ◽  
H Leung ◽  
A M Weiner
Keyword(s):  
Splice Site ◽  
Consensus Sequence ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen ◽  
Splice Sites ◽  
Small Nuclear Ribonucleoprotein ◽  
Antigen 5

The use of alternative 5' splice sites in the simian virus 40 early-transcription unit controls the ratio of large T to small t antigen during viral infection. To study the regulation of these alternative 5' splice sites, we made two mutants which improve the match of the large-T-antigen 5' splice site to the 5' splice site consensus sequence. Whether these mutants were assayed in vitro or in vivo, we found that the efficiency of large-T splicing is increased by improving the match of the large-T-antigen 5' splice site to the consensus. We conclude that the match of a 5' splice site is an important determinant of 5' splice site utilization and that the simian virus 40 large-T-antigen 5' splice site is almost certainly recognized by the U1 small nuclear RNA component of the U1 small nuclear ribonucleoprotein particle.

A novel protein factor is required for use of distal alternative 5' splice sites in vitro

1991 ◽  
Vol 11 (12) ◽  
pp. 5945-5953
Author(s):  
J E Harper ◽  
J L Manley
Keyword(s):  
Splice Site ◽  
Site Selection ◽  
Deae Cellulose ◽  
Simian Virus 40 ◽  
Nuclear Extract ◽  
Simian Virus ◽  
Splice Sites ◽  
Splice Site Selection ◽  
Small Nuclear Ribonucleoprotein

Adenovirus E1A pre-mRNA was used as a model to examine alternative 5' splice site selection during in vitro splicing reactions. Strong preference for the downstream 13S 5' splice site over the upstream 12S or 9S 5' splice sites was observed. However, the 12S 5' splice site was used efficiently when a mutant pre-mRNA lacking the 13S 5' splice site was processed, and 12S splicing from this substrate was not reduced by 13S splicing from a separate pre-mRNA, demonstrating that 13S splicing reduced 12S 5' splice site selection through a bona fide cis-competition. DEAE-cellulose chromatography of nuclear extract yielded two fractions with different splicing activities. The bound fraction contained all components required for efficient splicing of simple substrates but was unable to utilize alternative 5' splice sites. In contrast, the flow-through fraction, which by itself was inactive, contained an activity required for alternative splicing and was shown to stimulate 12S and 9S splicing, while reducing 13S splicing, when added to reactions carried out by the bound fraction. Furthermore, the activity, which we have called distal splicing factor (DSF), enhanced utilization of an upstream 5' splice site on a simian virus 40 early pre-mRNA, suggesting that the factor acts in a position-dependent, substrate-independent fashion. Several lines of evidence are presented suggesting that DSF is a non-small nuclear ribonucleoprotein protein. Finally, we describe a functional interaction between DSF and ASF, a protein that enhances use of downstream 5' splice sites.

scholarly journals A novel protein factor is required for use of distal alternative 5' splice sites in vitro.

1991 ◽  
Vol 11 (12) ◽  
pp. 5945-5953 ◽  
Author(s):  
J E Harper ◽  
J L Manley
Keyword(s):  
Splice Site ◽  
Site Selection ◽  
Deae Cellulose ◽  
Simian Virus 40 ◽  
Nuclear Extract ◽  
Simian Virus ◽  
Splice Sites ◽  
Splice Site Selection ◽  
Small Nuclear Ribonucleoprotein

Adenovirus E1A pre-mRNA was used as a model to examine alternative 5' splice site selection during in vitro splicing reactions. Strong preference for the downstream 13S 5' splice site over the upstream 12S or 9S 5' splice sites was observed. However, the 12S 5' splice site was used efficiently when a mutant pre-mRNA lacking the 13S 5' splice site was processed, and 12S splicing from this substrate was not reduced by 13S splicing from a separate pre-mRNA, demonstrating that 13S splicing reduced 12S 5' splice site selection through a bona fide cis-competition. DEAE-cellulose chromatography of nuclear extract yielded two fractions with different splicing activities. The bound fraction contained all components required for efficient splicing of simple substrates but was unable to utilize alternative 5' splice sites. In contrast, the flow-through fraction, which by itself was inactive, contained an activity required for alternative splicing and was shown to stimulate 12S and 9S splicing, while reducing 13S splicing, when added to reactions carried out by the bound fraction. Furthermore, the activity, which we have called distal splicing factor (DSF), enhanced utilization of an upstream 5' splice site on a simian virus 40 early pre-mRNA, suggesting that the factor acts in a position-dependent, substrate-independent fashion. Several lines of evidence are presented suggesting that DSF is a non-small nuclear ribonucleoprotein protein. Finally, we describe a functional interaction between DSF and ASF, a protein that enhances use of downstream 5' splice sites.

scholarly journals Stimulation of the Human Heat Shock Protein 70 Promoter in Vitro by Simian Virus 40 Large T Antigen

1989 ◽  
Vol 264 (27) ◽  
pp. 16160-16164
Author(s):  
I C Taylor ◽  
W Solomon ◽  
B M Weiner ◽  
E Paucha ◽  
M Bradley ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Shock Protein 70 ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen ◽  
Human Heat Shock Protein ◽  
Stimulation Of

Protein kinase activities in immune complexes of simian virus 40 large T-antigen and transformation-associated cellular p53 protein

1984 ◽  
Vol 4 (2) ◽  
pp. 232-239
Author(s):  
F Van Roy ◽  
L Fransen ◽  
W Fiers
Keyword(s):  
Monoclonal Antibodies ◽  
Immune Complex ◽  
Immune Complexes ◽  
Kinase Activity ◽  
P53 Protein ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen

Immune complex kinase assays in the simian virus 40 system were performed by incubation of immunoprecipitates containing tumor antigens with [gamma-32P]ATP, followed by analysis of any phosphoacceptor proteins. These assays yielded mainly the viral large T-antigen and, in particular, the associated cellular p53 as endogenous substrates. The nature of these substrates was confirmed by proteolysis techniques. Under specific conditions, casein could be used as an exogenous substrate as well. The kinase reactions showed preference for ATP and MgCl2 instead of GTP or MnCl2. Both phosphoserine and phosphothreonine, but in no case phosphotyrosine, were detected after an immune complex kinase reaction. Apparently, several in vivo phosphorylation sites were recognized in vitro in both large T-antigen and p53, but the presence of some artifactual sites could not be completely excluded. Although contaminating kinases were detectable in the immune complexes, at least the p53 molecules were phosphorylated in vitro in a more specific way. This followed from several characteristics of the immune complex kinase reactions and especially from the strong inhibition of p53 phosphorylation by two anti-large-T monoclonal antibodies. It was shown that large T-antigen showed associated kinase activity, although none of our results could unambiguously demonstrate an intrinsic kinase activity of this protein. Finally, anti-p53 monoclonal antibodies only slightly affected in vitro phosphorylation reactions, whereas a p53 molecule from a simian virus 40-free, chemically transformed human cell line was not phosphorylated in vitro under any condition tested. Thus, it is highly unlikely that the p53 molecule per se carries intrinsic or even associated kinase activities.

scholarly journals Short donor site sequences inserted within the intron of beta-globin pre-mRNA serve for splicing in vitro.

1988 ◽  
Vol 8 (10) ◽  
pp. 4484-4491 ◽  
Author(s):  
A Mayeda ◽  
Y Ohshima
Keyword(s):  
Consensus Sequence ◽  
Donor Site ◽  
Simian Virus 40 ◽  
Nuclear Extract ◽  
Simian Virus ◽  
T Antigen ◽  
Beta Globin ◽  
Vitro Assay ◽  
Active Donor

We constructed SP6-human beta-globin derivative plasmids that included possible donor site (5' splice site) sequences at a specified position within the first intron. The runoff transcripts from these templates truncated in the second exon were examined for splicing in a nuclear extract from HeLa cells. In addition to the products from the authentic donor site, a corresponding set of novel products from the inserted, alternative donor site was generated. Thus, a short sequence inserted within an intron can be an active donor site signal in the presence of an authentic donor site. The active donor site sequences included a 9-nucleotide consensus sequence, 14- or 16-nucleotide sequences at the human beta-globin first or second donor, and those at simian virus 40 large T antigen or small t antigen donor. These included 3 to 8 nucleotides of an exon and 6 to 8 nucleotides of an intron. The activity of the inserted donor site relative to that of the authentic donor site depended on the donor sequence inserted. The relative activity also strongly depended on the concentrations of both KCl (40 to 100 mM) and MgCl2 (1.6 to 6.4 mM). At the higher KCl concentrations tested, all the inserted, or proximate, donor sites were more efficiently used. Under several conditions, some inserted donor sites were more active than was the authentic donor site. Our system provides an in vitro assay for donor site activity of a sequence to be tested.

scholarly journals Protein kinase activities in immune complexes of simian virus 40 large T-antigen and transformation-associated cellular p53 protein.

1984 ◽  
Vol 4 (2) ◽  
pp. 232-239 ◽  
Author(s):  
F Van Roy ◽  
L Fransen ◽  
W Fiers
Keyword(s):  
Monoclonal Antibodies ◽  
Immune Complex ◽  
Immune Complexes ◽  
Kinase Activity ◽  
P53 Protein ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Large T Antigen

Immune complex kinase assays in the simian virus 40 system were performed by incubation of immunoprecipitates containing tumor antigens with [gamma-32P]ATP, followed by analysis of any phosphoacceptor proteins. These assays yielded mainly the viral large T-antigen and, in particular, the associated cellular p53 as endogenous substrates. The nature of these substrates was confirmed by proteolysis techniques. Under specific conditions, casein could be used as an exogenous substrate as well. The kinase reactions showed preference for ATP and MgCl2 instead of GTP or MnCl2. Both phosphoserine and phosphothreonine, but in no case phosphotyrosine, were detected after an immune complex kinase reaction. Apparently, several in vivo phosphorylation sites were recognized in vitro in both large T-antigen and p53, but the presence of some artifactual sites could not be completely excluded. Although contaminating kinases were detectable in the immune complexes, at least the p53 molecules were phosphorylated in vitro in a more specific way. This followed from several characteristics of the immune complex kinase reactions and especially from the strong inhibition of p53 phosphorylation by two anti-large-T monoclonal antibodies. It was shown that large T-antigen showed associated kinase activity, although none of our results could unambiguously demonstrate an intrinsic kinase activity of this protein. Finally, anti-p53 monoclonal antibodies only slightly affected in vitro phosphorylation reactions, whereas a p53 molecule from a simian virus 40-free, chemically transformed human cell line was not phosphorylated in vitro under any condition tested. Thus, it is highly unlikely that the p53 molecule per se carries intrinsic or even associated kinase activities.

scholarly journals Multiple cis-acting sequence elements are required for efficient splicing of simian virus 40 small-t antigen pre-mRNA.

1988 ◽  
Vol 8 (9) ◽  
pp. 3582-3590 ◽  
Author(s):  
X Y Fu ◽  
J D Colgan ◽  
J L Manley
Keyword(s):  
Alternative Splicing ◽  
Branch Point ◽  
Splice Site ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Specific Sequence ◽  
Small T Antigen

We have determined the effects of a number of mutations in the small-t antigen mRNA intron on the alternative splicing pattern of the simian virus 40 early transcript. Expansion of the distance separating the small-t pre-mRNA lariat branch point and the shared large T-small t 3' splice site from 18 to 29 nucleotides (nt) resulted in a relative enhancement of small-t splicing in vivo. This finding, coupled with the observation that large-T pre-RNA splicing in vitro was not affected by this expansion, suggests that small-t splicing is specifically constrained by a short branch point-3' splice site distance. Similarly, the distance separating the 5' splice site and branch point (48 nt) was found to be at or near a minimum for small-t splicing, because deletions in this region as small as 2 nt dramatically reduced the ratio of small-t to large-T mRNA that accumulated in transfected cells. Finally, a specific sequence within the small-t intron, encompassing the upstream branch sites used in large-T splicing, was found to be an important element in the cell-specific pattern of early alternative splicing. Substitutions within this region reduced the ratio of small-t to large-T mRNA produced in HeLa cells but had only minor effects in human 293 cells.

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