Abstract
The promoter structure of the known small nuclear RNA (snRNA) genes contains two major effectors of transcriptional activity: a proximal sequence element and a distal sequence element. In addition to these two functional elements (called elements B and D), the human U1 snRNA gene contains at least three minor elements (elements A, C, and E) that contribute to overall transcriptional efficiency (Murphy, J.T., Skuzeski, J.M., Lund, E., Steinberg, T.H., Burgess, R.R., and Dahlberg, J.E. (1987) J. Biol. Chem. 262, 1795-1803). To elucidate further the function of these transcription elements, we carried out a computer search to look for sequences in the U1 gene homologous to known transcription factor consensus sequences. Where such homology was found, DNase I and MPE-Fe(II) (methidiumpropyl-EDTA-Fe(II] footprinting was employed to study the interactions of these promoter regions with proteins partially purified from extracts of HeLa cells or human placenta. Footprints were observed over element D (the distal element) corresponding to sequences homologous to the octanucleotide binding protein (OCTA) and activator protein 1 (AP1). Protection was also observed over element B (the proximal element) corresponding to possible sites for stimulatory protein 1 (Sp1), enhancer core, major late transcription factor (MLTF), and a U1-specific transcription factor. Prior to this study, no specific transcription factor footprints had been observed over proximal elements of any snRNA gene. Footprints were also found over elements A and E. The results of the computer search and the footprinting are discussed in light of what is known about snRNA promoter activity.
Highlights
From the McArdle Laboratory for Cancer Research and the §Departmentof Physiological Chemistry, University of Wisconsin, Madison, Wisconsin 53706
Results of the Computer Search-Fig. lA summarizes the location of transcription elements in the U1 gene 5'-flanking region and the location of several direct or inverted repeats
Homologous sites were found based on the following level of stringency of fit: 1)perfect matches for ATF, for the consensus sequence for c-myc promoters, and for the CCAAT binding T F family (CTF, CBF, CBP); 2) one mismatch for MLTF, AP1, enhancer core (EnhC); and 3) two mismatches for Spl and OCTA
Summary
Results of the Computer Search-Fig. lA summarizes the location of transcription elements in the U1 gene 5'-flanking region and the location of several direct or inverted repeats. Footprinting within Elements A and B-We examined the protect both the OCTA site and part of the AP1 site from ability of extracts enriched for various TFs tobind to the U1 MPE-Fe(I1) cleavage Note that both fractions D7 and D9 promoter region. In lane 0 7 (fraction D7) two distinct foot- and the Murine dhfr Promoter using a Spl-enriched HeLa prints cover the sites for Spl and enhancer core, while lune Cell Nuclear Extract-Fig. 5 shows the results of both direct.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
