DB Lecture 24: Regulated Transcription

Question 1

Describe the structure of transcription factors.

Answer 1

DNA binding domain (recognizes a specific DNA sequence)
activation domain(interacts with other proteins to enhance the transcription rate)

Question 2

List the common DNA biding motifs of transcription factors.

Answer 2

helix-turn-helix motif (three alpha helices- contact made between amino-acids in txn factor and DNA nucleotides)
zinc finger motif (one alpha helix and one beta sheet with four zinc fingers)

Question 3

What is the function of co-activators?

Answer 3

change the state of local chromatin

Question 4

What is HAT?

Answer 4

histone acetyl transferase
histone modifying enzyme that acetylates histone lysine residue which recruits other proteins that have domains that recognize acetylated histone tails and serve to attract basal transcription factors or chromatin remodeling complexes

Question 5

What is HDAC?

Answer 5

histone deacetylase
enzyme that reverses acetylation of histones
usually has an inhibitory effect

Question 6

What other functions do chromatin remodeling complexes perform other than chromatin modification?

Answer 6

change the histone protein composition of the nucleosome (this changes chromatin structure in the nucelosome)

Question 7

What is MeCP2?

Answer 7

a protein that binds to 5-methyl cytosine and recruits a histone deacetylase
example of methylation of C residues in CpG dinucleotides that can serve as a recognition site for binding proteins that recruit enzymes that alter the properties of local chromatin