Wikiversity

Gene transcriptions/Elements/X core promoters

< Gene transcriptions/Elements
(Redirected from X core promoter element 1)

The core promoter element X core promoter element 1 (XCPE1) directs activator-, mediator-, protein-dependent but TFIID-independent RNA polymerase II transcription from TATA box-less promoters.[1]

The image shows a group of people gathered to promote a computer game. Credit: - EMR -.

This promoter element appears to be exclusively human such as the group in the image at the right.

Consensus sequences edit

Main articles: Gene transcriptions/Consensus sequences and Consensus sequences

"[T]he X gene core promoter element 1 ... is located between nucleotides -8 and +2 relative to the transcriptional start site (+1) and has a consensus sequence of G/A/T-G/C-G-T/C-G-G-G/A-A-G/C+1-A/C."[1]

Gene expressions edit

Main articles: Genes/Expressions and Gene expressions

Although it is harder to regulate the transcription of genes with multiple transcription start sites, "variations in the expression of a constitutive gene would be minimized by the use of multiple start sites."[2]

Human genes edit

Main articles: Genes/Human and Human genes

"XCPE1 is ... found in the core promoter regions of about 1% of human genes, particularly in poorly characterized TATA-less genes."[1]

Gene transcriptions edit

Main article: Gene transcriptions

"From a teleological standpoint, this arrangement [of focused promoters] is consistent with the notion that it would be easier to regulate the transcription of a gene with a single transcription start site than one with multiple start sites."[2]

Focused promoters edit

Main articles: Gene transcriptions/Promoters/Focused and Focused promoters

"In focused transcription, there is either a single major transcription start site or several start sites within a narrow region of several nucleotides. Focused transcription is the predominant mode of transcription in simpler organisms."[2]

"Focused transcription initiation occurs in all organisms, and appears to be the predominant or exclusive mode of transcription in simpler organisms."[2]

"In vertebrates, focused transcription tends to be associated with regulated promoters".[2]

"The analysis of focused core promoters has led to the discovery of sequence motifs such as the TATA box, BREu (upstream TFIIBrecognition element), Inr (initiator), MTE (motif ten element), DPE (downstream promoter element), DCE (downstream core element), and XCPE1 (Xcore promoter element 1) [...]."[2]

Dispersed promoters edit

Main articles: Gene transcriptions/Promoters/Dispersed and Dispersed promoters

"In dispersed transcription, there are several weak transcription start sites over a broad region of about 50 to 100 nucleotides. Dispersed transcription is the most common mode of transcription in vertebrates. For instance, dispersed transcription is observed in about two-thirds of human genes."[2]

In vertebrates, "dispersed transcription is typically observed in constitutive promoters in CpG islands."[2]

Core promoters edit

Main articles: Gene transcriptions/Core promoters and Core promoters

"Focused transcription typically initiates within the Inr, and the A nucleotide in the Inr consensus is usually designed as the “+ 1” position, whether or not transcription actually initiates at that particular nucleotide. This convention is useful because other core promoter motifs, such as the MTE and DPE, function with the Inr in a manner that exhibits a strict spacing dependence with the Inr consensus sequence (and hence, the A + 1 nucleotide) rather than the actual transcription start site (Burke and Kadonaga, 1997, Kutach and Kadonaga, 2000 and Lim et al., 2004)."[2]

"NC2 (negative cofactor 2; also known as Dr1-Drap1) [...] was identified as repressor of TATA-dependent transcription [...]."[2]

"Several core promoter elements have been previously identified in eukaryotes, but those cannot account for transcription from most RNA polymerase II-transcribed genes."[1]

Hypotheses edit

Main article: Hypotheses
  1. XCPE1 does not participate in the transcription of A1BG.

See also edit

References edit

  1. ↑ 1.0 1.1 1.2 1.3 Yumiko Tokusumi, Ying Ma, Xianzhou Song, Raymond H. Jacobson, and Shinako Takada (March 2007). "The New Core Promoter Element XCPE1 (X Core Promoter Element 1) Directs Activator-, Mediator-, and TATA-Binding Protein-Dependent but TFIID-Independent RNA Polymerase II Transcription from TATA-Less Promoters". Molecular and Cellular Biology 27 (5): 1844-58. doi:10.1128/MCB.01363-06. PMID 17210644. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1820453/. Retrieved 2013-02-09. 
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 Tamar Juven-Gershon and James T. Kadonaga (15 March 2010). "Regulation of gene expression via the core promoter and the basal transcriptional machinery". Developmental Biology 339 (2): 225-9. doi:10.1016/j.ydbio.2009.08.009. http://www.sciencedirect.com/science/article/pii/S0012160609011166. Retrieved 2016-01-16. 

Further reading edit

External links edit

Retrieved from "https://en.wikiversity.org/w/index.php?title=Gene_transcriptions/Elements/X_core_promoters&oldid=2120538"