# Gene transcriptions/Distal promoters

A distal promoter is a distant (in numbers of nucleotides) portion of the promoter for a particular gene.
This distal sequence is upstream of the gene.
It is a region of DNA that may contain additional regulatory elements, often with a weaker influence than the proximal promoter.

## Promoters

A promoter is a region of DNA that facilitates the transcription of a particular gene. "Promoters can be about 100–1000 [nucleotides] long.
A promoter is on the template strand for the gene and near the gene in numbers of nucleotides (nts) along the DNA template strand. Usually, the promoter lies within the string of nucleotides between genes.
Some promoters are called constitutive as they are active in all circumstances in the cell, while others are regulated becoming active in response to specific stimuli.
These specific stimuli for a gene find a receptive portion within that gene's promoter.
In the case of genes that are used to produce proteins, the RNA polymerase II holoenzyme that actually performs the transcription from the template strand needs to find chemical cues for attachment to the DNA and where to begin transcription. Preceding this are chemical cues for which DNA strand is the template strand and in what direction transcription is to be performed.
A promoter contains cues for the number of copies to be transcribed and when to stop making copies.
Once the holoenzyme is assembled and attached to the promoter, the transcription start site (TSS) is transcribed as the first nucleotide of the pre-messenger RNA.
When a transcription factory is nearby, chemical cues begin the movement of the euchromatin to the factory. The already assembled RNA polymerase II holoenzyme attaches per appropriate cues and begins transcription at the designated TSS. Some genes have more than one TSS.

## Distals

Def. remote "from the point of attachment or origin" is called distal.

## Theoretical distal promoters

Here's a theoretical definition:
Def. an upstream region between -2.0 knts to -1.5 knts for a gene that can exist in a supercoiled conformation with this region to be actively transcribed is called a distal promoter.

## CYP11A

The "upstream regions of the human CYP11A and bovine CYP11B genes [have] a distal promoter in each gene. The distal promoters are located at −1.8 to −1.5 kb in the upstream region of the CYP11A gene and −1.5 to −1.1 kb in the upstream region of the CYP11B gene."

## β$^A$-globin genes

"Using cloned chicken β$^A$-globin genes, either individually or within the natural chromosomal locus, enhancer-dependent transcription is achieved in vitro at a distance of 2 kb with developmentally staged erythroid extracts. This occurs by promoter derepression and is critically dependent upon DNA topology. In the presence of the enhancer, genes must exist in a supercoiled conformation to be actively transcribed, whereas relaxed or linear templates are inactive. Distal protein–protein interactions in vitro may be favored on supercoiled DNA because of topological constraints."

## FCER1A

Fc fragment of IgE, high affinity I, receptor for; alpha polypeptide, also known as FCER1A, is a protein which in humans is encoded by the FCER1A gene.
The human FCER1A may be regulated using its distal promoter.

## HBE1

Hemoglobin subunit epsilon is a protein that in humans is encoded by the HBE1 gene.
There is a G to A substitution in the distal CCAAT box of the A gamma-globin gene in Greek hereditary persistence of fetal haemohlobin.
The distal promoter element ACACCC has a role regarding base substitution at position -88 in a beta-thalassemic globin gene.

## HIST1H1C

Histone H1.2 is a protein that in humans is encoded by the HIST1H1C gene.
A distal promoter in the S-phase has a role in the control of the human H1.2 histone gene transcription.

## Prolactins

In humans, prolactin is produced at least in the pituitary, decidua, myometrium, breast, lymphocytes, leukocytes and prostate.
Pituitary PRL is controlled by the Pit-1 transcription factor and ultimately dopamine, extrapituitary PRL is controlled by a superdistal promoter and apparently unaffected by dopamine.
In decidual cells and in lymphocytes the distal promoter and thus prolactin expression is stimulated by [cyclic adenosine monophosphate] cAMP. [Responsiveness] to cAMP is mediated by an imperfect cAMP–responsive element and two CAAT/enhancer binding proteins (C/EBP). Progesterone has been observed to upregulate prolactin synthesis in the endometrium but decreases it in myometrium and breast glandular tissue. However breast and other tissues may also express the Pit-1 promoter in addition to the distal promoter.

## SCP2

"This gene encodes two proteins: sterol carrier protein X (SCPx) and sterol carrier protein 2 (SCP2), as a result of transcription initiation from 2 independently regulated promoters. The transcript initiated from the proximal promoter encodes the longer SCPx protein, and the transcript initiated from the distal promoter encodes the shorter SCP2 protein, with the 2 proteins sharing a common C-terminus."

## Six3OS1

Six3OS1 is a long non-coding RNA. It was originally identified in the murine embryonic and postnatal retina. It is located in the distal promoter region of the gene encoding Six3, a homeodomain transcription factor. It regulates the activity of Six3 in the developing mouse retina, by binding to transcriptional co-regulators of Six3 and to histone modification enzymes and acting as a transcriptional scaffold.