Selective factor 1

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).[1][2]

Role of transcription factor in gene expression regulation

Discovery

SL1 was discovered by Robert Tjian and his colleagues in 1985 when they separated a HeLa cell extract into two functional fractions.[3] 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.[4] That is, it could distinguish between the human and mouse rRNA promoter,[5] and added increasing amount of human template at the expense of the mice template.[6] 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.[7] 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.[8]

Structure

SL1 is composed of the TATA-binding protein and three TAF (TATA box-binding protein-associated factor) subunits (TAF1A, TAF1B, and TAF1C).[9] 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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