Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The TATA-box-binding protein TBP exists in the cell complexed with different sets of TBP-associated factors (TAFs). In general, each of these TBP-TAF complexes is dedicated to transcription by a single RNA polymerase. Thus, SL1, TFIID and TFIIIB are required for transcription by polymerases I, II and III, respectively. Here we characterize a fourth TBP-TAF complex called SNAPc. Unlike the other TBP-TAF complexes, SNAPc is implicated in transcription by two types of polymerases; it is required for transcription of both the RNA polymerase II and III small-nuclear RNA genes and binds specifically to the proximal sequence element PSE, a non-TATA-box basal promoter element common to these two types of genes. In addition to TBP, SNAPc is composed of at least three TAFs, SNAP43, SNAP45 and SNAP50. The predicted amino-acid sequence of SNAP43 reveals that it corresponds to a new protein.
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PMID:A TBP-TAF complex required for transcription of human snRNA genes by RNA polymerase II and III. 771 7

The RNA polymerase II and III small nuclear RNA (snRNA) promoters contain a common basal promoter element, the proximal sequence element (PSE). The PSE binds a multisubunit complex we refer to as the snRNA activating protein complex (SNAPc). At least four polypeptides are visible in purified SNAPc preparations, which migrate with apparent molecular masses of 43, 45, 50, and 190 kDa on SDS/polyacrylamide gels. In addition, purified preparations of SNAPc contain variable amounts of TATA box binding protein (TBP). An important question is whether the PSEs of RNA polymerase II and III snRNA promoters recruit the exact same SNAP complex or slightly different versions of SNAPc, differing, for example, by the presence or absence of a subunit. To address this question, we are isolating cDNAs encoding different subunits of SNAPc. We have previously isolated the cDNA encoding the 43-kDa subunit SNAP43. We now report the isolation of the cDNA that encodes the p45 polypeptide. Antibodies directed against p45 retard the mobility of the SNAPc-PSE complex in an electrophoretic mobility shift assay, indicating that p45 is indeed part of SNAPc. We therefore refer to this protein as SNAP45. SNAP45 is exceptionally proline-rich, interacts strongly with TBP, and, like SNAP43, is required for both RNA polymerase II and III transcription of snRNA genes.
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PMID:The SNAP45 subunit of the small nuclear RNA (snRNA) activating protein complex is required for RNA polymerase II and III snRNA gene transcription and interacts with the TATA box binding protein. 863 57

The human RNA polymerase II and III snRNA promoters share a common basal element, the proximal sequence element (PSE), which is recognized by a complex we refer to as the snRNA-activating protein complex (SNAPc). Biochemical purifications suggest that SNAPc is composed of at least four polypeptides of 43, 45, 50 and 190 kDa, as well as variable amounts of the TATA box binding protein, TBP. cDNAs encoding the 43 and 45 kDa subunits, SNAP43 and SNAP45, have been isolated, but there is no evidence that either of these subunits contacts DNA. Here we report the isolation of cDNAs encoding the 50 kDa subunit of SNAPc, SNAP50. The open reading frame predicts a 411 amino acid protein, which contains two potential zinc finger motifs. Depletions with anti-SNAP50 antibodies inhibit RNA polymerase II and III snRNA gene transcription in vitro. SNAP50 interacts with SNAP43 in co-immunoprecipitation experiments, but not with SNAP45 or TBP. UV cross-linking experiments suggest that SNAP50 contacts DNA in the SNAP complex. These results are consistent with the same core SNAP complex recognizing the PSEs of RNA polymerase II and III snRNA promoters, and provide an initial view of the architecture of the SNAP complex.
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PMID:Cloning and characterization of SNAP50, a subunit of the snRNA-activating protein complex SNAPc. 900 88

The human RNA polymerase II and III snRNA promoters have similar enhancers, the distal sequence elements (DSEs), and similar basal promoter elements, the proximal sequence elements (PSEs). The DSE, which contains an octamer motif, binds broadly expressed activator Oct-1. The PSE binds a multiprotein complex referred to as SNAPc or PTF. On DNAs containing both an octamer site and a PSE, Oct-1 and SNAPc bind cooperatively. SNAPc consists of at least four stably associated subunits, SNAP43, SNAP45, SNAP50, and SNAP190. None of the three small subunits, which have all been cloned, can bind to the PSE on their own. Here we report the isolation of cDNAs corresponding to the largest subunit of SNAPc, SNAP190. SNAP190 contains an unusual Myb DNA binding domain consisting of four complete repeats (Ra to Rd) and a half repeat (Rh). A truncated protein consisting of the last two SNAP190 Myb repeats, Rc and Rd, can bind to the PSE, suggesting that the SNAP190 Myb domain contributes to recognition of the PSE by the SNAP complex. SNAP190 is required for snRNA gene transcription by both RNA polymerases II and III and interacts with SNAP45. In addition, SNAP190 interacts with Oct-1. Together, these results suggest that the largest subunit of the SNAP complex is involved in direct recognition of the PSE and is a target for the Oct-1 activator. They also provide an example of a basal transcription factor containing a Myb DNA binding domain.
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PMID:The large subunit of basal transcription factor SNAPc is a Myb domain protein that interacts with Oct-1. 941 84

The basal transcription factor SNAPc binds to the PSE, a core element in the RNA polymerase II and III human snRNA promoters. SNAPc contains at least four subunits, but it has not been possible to assemble a fully defined recombinant SNAPc. Here we reconstitute SNAPc from five recombinant subunits, SNAP43, SNAP45, SNAP50, SNAP190, and a newly identified subunit, SNAP19. This recombinant complex binds specifically to the PSE and directs both RNA polymerase II and III snRNA gene transcription. Thus, the same core SNAPc nucleates the assembly of two classes of initiation complexes.
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PMID:SNAP19 mediates the assembly of a functional core promoter complex (SNAPc) shared by RNA polymerases II and III. 973 65

The nucleation of RNA polymerases I-III transcription complexes is usually directed by distinct multisubunit factors. In the case of the human RNA polymerase II and III small nuclear RNA (snRNA) genes, whose core promoters consist of a proximal sequence element (PSE) and a PSE combined with a TATA box, respectively, the same multisubunit complex is involved in the establishment of RNA polymerase II and III initiation complexes. This factor, the snRNA-activating protein complex or SNAP(c), binds to the PSE of both types of promoters and contains five types of subunits, SNAP190, SNAP50, SNAP45, SNAP43, and SNAP19. SNAP(c) binds cooperatively with both Oct-1, an activator of snRNA promoters, and in the RNA polymerase III snRNA promoters, with TATA-binding protein, which binds to the TATA box located downstream of the PSE. Here we have defined subunit domains required for SNAP(c) subunit-subunit association, and we show that complexes containing little more than the domains mapped here as required for subunit-subunit contacts bind specifically to the PSE. These data provide a detailed map of the subunit-subunit interactions within a multifunctional basal transcription complex.
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PMID:A map of protein-protein contacts within the small nuclear RNA-activating protein complex SNAPc. 1105 76

Human small nuclear (sn) RNA genes are transcribed by either RNA polymerase II or III depending upon the arrangement of their core promoter elements. Regardless of polymerase specificity, these genes share a requirement for a general transcription factor called the snRNA activating protein complex or SNAP(C). This multi-subunit complex recognizes the proximal sequence element (PSE) commonly found in the upstream promoters of human snRNA genes. SNAP(C) consists of five subunits: SNAP190, SNAP50, SNAP45, SNAP43, and SNAP19. Previous studies have shown that a partial SNAP(C) composed of SNAP190 (1-514), SNAP50, and SNAP43 expressed in baculovirus is capable of PSE-specific DNA binding and transcription of human snRNA genes by RNA polymerases II and III. Expression in a baculovirus system yields active complex but the concentration of such material is insufficient for many bio-analytical methods. Herein, we describe the co-expression in Escherichia coli of a partial SNAP(C) containing SNAP190 (1-505), SNAP50, SNAP43, and SNAP19. The co-expressed complex binds DNA specifically and recruits TBP to U6 promoter DNA. Importantly, this partial complex functions in reconstituted transcription of both human U1 and U6 snRNA genes by RNA polymerases II and III, respectively. This co-expression system will facilitate the functional characterization of this unusual multi-protein transcription factor that plays an important early role for transcription by two different polymerases.
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PMID:Co-expression of multiple subunits enables recombinant SNAPC assembly and function for transcription by human RNA polymerases II and III. 1660 80