Introduction Types of Transcription factors involves in different Polymerase initiation complex Structure of transcription factor Role of transcription factor Significance

1. TRANSCRIPTION
FACTORS
Presented by
PRASHANT VC
DEPT OF ZOOLOGY
GUK

2. CONTENTS
Introduction
Types
Transcription factors involves in different
Polymerase initiation complex
Structure of transcription factor
Role of transcription factor
Significance
References

3. INTRODUCTION
• Transcription factor is a protein that binds to
specific DNA sequences.
• About 10% of the gene in the human genome
encode TF.
• RNA pol is able to initiate transcription if
additional proteins are added to reaction such
proteins are known as TF.

4. TYPES OF TRANSCRIPTION FACTORS
• Divided into the following three groups:
• General transcription factor
• Upstream transcription factor
• Inducible or regulatory transcription factor.

5. GENERALTRANSCRIPTIONFACTOR
• Required for initiation of transcription at all the
promoter.
• The different basal factors are as follows:
• TFIID
• TFIIB
• TFIIF
• TFIIE
• TFIIH

6. UPSTREAMTRANSCRIPTIONFACTOR
• These TF are recognize specific short
sequences located upstream of the start point.
• These factors include :
• SP1
• CTF family
• CP1 family
• OCT-1
• OCT-2

7. REGULATORYTRANSCRIPTIONFACTOR
• They have a regulatory role.
• Regulatory factors may be defined as a group
of proteins,which bind to specific sequences in
the promoter region of certain specific classes
of genes & regulate their transcription.

8. THEPROCESSOF
TRANSCRIPTION

9. TRANSCRIPTIONBY RNAPOL-I

10. TRANSCRIPTIONBY RNAPOL-II

11. TRANSCRIPTIONBY RNAPOL-III

12. STRUCTUREOF TRANSCRIPTIONFACTOR
• Transcription factors contain at least two
domains:-
• DNA binding domain- binds to a specific
sequence of base pair in the DNA.
• Activation domain- it regulate transcription
by interacting with other proteins.

13. DNABINDINGDOMAIN
• There are several groups of proteins that
regulate transcription by using particular
motifs to bind DNA.
• Helix- loop-helix proteins
• Leucine zipper proteins
• Zinc finger proteins

14. Helix-loop-Helixproteins
• It has highly basic
amino acids which
binds to DNA, so also
called bHLH

15. Leucine-zipper proteins
• The DBD of TF
contains the
hydrophobic
amino acid at
every 7th
position in the
sequence.

16. ZINCFINGERPROTEINS
It was originally found
in the factor
TFIIIA.
ß- Sheet coordinately
bind a zinc ion

17. ROLEOF TRANSCRIPTIONFACTOR
Factor No. of
Subunit
mass
( KD)
function
TFIIA 3 69 Stabilize TBP & TAF bind
TFIIB 1 35 Recognize promoter, accurately
position RNA pol at the start site of
transcription
TFIID
TBP 1 38 Recognize TATA Box
TAF ≥12 ≥ 960 Regulate DNA binding by TBP

18. TFIIE 2 165 Recruits TFIIH & stimulate helicase
activity
TFIIF 2 87 Attracts & regulate TFIIH, facilitates
promoter targeting
TFIIH 9 470 Unwinds DNA at start point

19. clinicalSIGNIFICANCE
• Mutation in p53 is a cause of Li- Fraumani
syndrome, which is a rare form of inherited
cancer, i.e. Brain tumor, leukemia, lung
cancer, pancreatic cancer.
• Xeroderma pigmentosum (or susceptibility
towards skin cancer):High sensitivity for UV
rays, DNA repair system is affected, skin &
eye sensitivity.

20. TRANSCRIPTIONINITIATION
WITHRNAPOL-II

21. REFERENCES
• B.D. Singh; Genetics; First Edition (2003) Reprinted 2006;
Kalayani Publishers ; New Delhi, Noida.
• Lodish, H., Berk, A., Matsudaira, P., Kaiser, C.A., Krieger,
M., Scott, M.P., Zipursky, S.L., Darnell, J., (2004), Molecular
Cell Biology, V-Edition; W.H. Freeman & Company, New
York, (U.S.A.),P :460-475.

22. THANKS