What is the TATA box in transcription?
A TATA box is a DNA sequence that indicates where a genetic sequence can be read and decoded. It is a type of promoter sequence, which specifies to other molecules where transcription begins. Many eukaryotic genes have a conserved TATA box located 25-35 base pairs before the transcription start site of a gene. …
What are TATA and CAAT box?
A CAAT box (also CAT box) is a region of nucleotides with the following consensus sequence: 5′ GGCCAATCT 3′. The CAAT box is located about 75-80 bases upstream of the transcription initiation site and about 150 bases upstream of the TATA box.
What does TATA box detect?
The TATA Box The TATA-binding protein (sometimes referred to as TBP) recognizes this TATA sequence and binds to it, creating a landmark that marks the start site of transcription.
What happens if the TATA box is deleted?
Deletion of a TATA box results in loss of the corresponding cap sites. An insertion of 7 bp between the right TATA box and corresponding cap sites results in a shift of the position of the cap sites, so that the original distance of TATA box to cap sites is conserved as much as possible.
Why TATA box is important?
The TATA box is essential for transcription and binds either TBP or the Acanthamoeba version of TFIID (32). The start site region is not essential, but serves to constrain the positioning of RNA polymerase II (24).
Do prokaryotes have TATA box?
Only eukaryotes and archaea, however, contain this TATA box. Most prokaryotes contain a sequence thought to be functionally equivalent called the Pribnow box which usually consists of the six nucleotides, TATAAT.
What is the function of 5 cap?
The 5′ cap is added to the first nucleotide in the transcript during transcription. The cap is a modified guanine (G) nucleotide, and it protects the transcript from being broken down. It also helps the ribosome attach to the mRNA and start reading it to make a protein.
How is 5 Cap added?
5′ End Capping The cap is added by the enzyme guanyl transferase. This enzyme catalyzes the reaction between the 5′ end of the RNA transcript and a guanine triphosphate (GTP) molecule. In the reaction, the beta phosphate of the RNA transcript displaces a pyrophosphate group at the 5′ position of the GTP molecule.