TRANSCRIPTION FACTORS.pptx

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 R eferences

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. GENERAL TRANSCRIPTION FACTOR Required for initiation of transcription at all the promoter. The different basal factors are as follows: TFIID TFIIB TFIIF TFIIE TFIIH

6. UPSTREAM TRANSCRIPTION FACTOR 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. REGULATORY TRANSCRIPTION FACTOR 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. THE PROCESS OF TRANSCRIPTION

9. TRANSCRIPTION BY RNA POL-I

10. TRANSCRIPTION BY RNA POL-II

11. TRANSCRIPTION BY RNA POL-III

12. STRUCTURE OF TRANSCRIPTION FACTOR 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. DNA BINDING DOMAIN 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-Helix proteins 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. ZINC FINGER PROTEINS It was originally found in the factor TFIIIA. ß- Sheet coordinately bind a zinc ion

17. ROLE OF TRANSCRIPTION FACTOR 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. clinical SIGNIFICANCE 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. TRANSCRIPTION INITIATION WITH RNA POL-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