Question

What is a silencer? Is it present upstream or downstream of a promoter? Does each gene seq always have a silencer? ( like promoter is required for transcription)

Answer 1

@nincompoop

Answer 2

A silencer is a DNA sequence some distance from the transcription start site, where a repressor of transcription may bind.

Answer 3

In addition to the six general transcription factors eukaryotic cells contain many other proteins that interact with DNA and other transcription factors that repress or stimulate transcription of class 2 genes (genes transcribed by RNAP II). The regulatory proteins are known as activators and repressors, and their target DNA sites are known as enhancers and silencers, respectively. An enhancer is not typically essential for transcription unlike promoters however enhancers greatly increase the rate of transcription. Enhancers or silencers do not need or have a fixed position and orientations unlike promoters which are always a short distance from the transcription start site. Many enhancers are located upstream of transcribed sequences, the proteins that bind to them are often called upstream transcription factors. A good example originated from the insulin producing genes researched by William Rutter.

Answer 4

@warpedvibration thanks a ton!! :-)