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Selective factor 1

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Mammalian protein found in Homo sapiens
Role of transcription factor in gene expression regulation

Selective factor 1 (also known as SL1) is a transcription factor that binds to the promoter of genes and recruits a preinitiation complex to which RNA polymerase I will bind to and begin the transcription of ribosomal RNA (rRNA).

Discovery

SL1 was discovered by Robert Tjian and his colleagues in 1985 when they separated a HeLa cell extract into two functional fractions. One factor has RNA polymerase I activity, but no ability to initiate accurate transcription of a human rRNA template. This transcription factor, SL1, showed species specificity. That is, it could distinguish between the human and mouse rRNA promoter, and added increasing amount of human template at the expense of the mice template. Tijian and coworkers went on to show that by footprinting a partially purified polymerase 1 preparation could bind to the human rRNA promoter. In particular it causes a footprint over a region of the UCE called A site. This binding is not due to polymerase I itself but to a transcription factor called upstream binding factor, UBF.

Function

SLI functions in assembling the transcription preinitiation complex. It is also a major determinant of species-specificity in ribosomal RNA gene transcription. Research suggests that UBF and SL1 act synergistically to stimulate transcription. Recent investigation also suggests that SL1 is a target for cancer therapy.

Structure

SL1 is composed of the TATA-binding protein and at least four TAF (TATA box-binding protein-associated factor) subunits (TAF1A, TAF1B,TAF1C and TAF1D). It is therefore possible to inhibit SL1 activity with anti-TBP antibodies.

See also

References

  1. Tuan JC, Zhai W, Comai L (1999). "Recruitment of TATA-binding protein-TAFI complex SL1 to the human ribosomal DNA promoter is mediated by the carboxy-terminal activation domain of upstream binding factor (UBF) and is regulated by UBF phosphorylation". Molecular and Cellular Biology. 19 (4): 2872–9. doi:10.1128/MCB.19.4.2872. PMC 84080. PMID 10082553.
  2. Lewin's Genes XI. Retrieved 2014-08-10.
  3. Hochheimer A, Tjian R (2003). "Diversified transcription initiation complexes expand promoter selectivity and tissue-specific gene expression". Genes & Development. 17 (11): 1309–20. doi:10.1101/gad.1099903. PMID 12782648.
  4. Hempel WM, Cavanaugh AH, Hannan RD, Taylor L, Rothblum LI (1996). "The species-specific RNA polymerase I transcription factor SL-1 binds to upstream binding factor". Molecular and Cellular Biology. 16 (2): 557–63. doi:10.1128/MCB.16.2.557. PMC 231034. PMID 8552083.
  5. The Nucleolus. 2011-09-15. Retrieved 2014-08-10.
  6. Learned RM, Cordes S, Tjian R (1985). "Purification and characterization of a transcription factor that confers promoter specificity to human RNA polymerase I". Molecular and Cellular Biology. 5 (6): 1358–69. doi:10.1128/MCB.5.6.1358. PMC 366865. PMID 3929071.
  7. "Patent US5637686 - Tata-binding protein associated factor, nucleic acids - Google Patents". Retrieved 2014-08-10.
  8. Villicaña C, Cruz G, Zurita M (2014). "The basal transcription machinery as a target for cancer therapy". Cancer Cell International. 14 (1): 18. doi:10.1186/1475-2867-14-18. PMC 3942515. PMID 24576043.
  9. Friedrich JK, Panov KI, Cabart P, Russell J, Zomerdijk JC (2005). "TBP-TAF complex SL1 directs RNA polymerase I pre-initiation complex formation and stabilizes upstream binding factor at the rDNA promoter". The Journal of Biological Chemistry. 280 (33): 29551–8. doi:10.1074/jbc.M501595200. PMC 3858828. PMID 15970593.
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