Translation Flashcards
Give some examples of zinc-finger proteins
Members include nuclear receptors such as:
Estrogen Receptor
Androgen Receptor
Retinoic acid receptor
What’re some examples of homeodomain proteins? (helix-turn-helix)
Hox family
Pit1
Msx
Give examples of base leucine zipper proteins (bZIP)
c-fos
c-jun
Give some examples of helix-loop-helix motif (bHLH)
MyoD
myogenin
Myf5
List the 2 classes of chromatin remodeling factors and briefly describe how they work.
- ) DNA-dependent ATPases (SWI/SNF) - disrupt histone octamers and DNA. Uses ATP hydrolysis to move histone along DNA
- ) Factors that reversible modify histone through acetylation (HATs and HDACs)
The basic structural unit of chromatin is the ________, which consists of a core of _______ proteins around which the DNA is wound
nucleosome
histone
The ________ end of histones are rich in _______, which can be reversibly modified by acetylation, _______, _______, and ________. Acetylation is associated with __________.
N-terminal
Lysine residues
phosphorylation, methylation, ubiquitination
gene control
Describe how activators/repressors modulate transcription via their interaction with general transcriptional machinery vs with chromatin
- ) Interact with general transcription factors/polymerase II associated proteins to influence initiation of elongation of the primary transcript
- ) Interact with chromatin to regulate accessibility of DNA to Pl II transcriptional apparatus.
List at least 4 mechanisms by which sequence-specific DNA binding proteins are regulated
- ) The conformation of the DNA-binding protein can be altered by ligand binding
- ) Entry into the nucleus can be regulated.
- ) The amount of transcription factor in the cell can be regulated
- ) DNA binding can be regulated
- ) Phosphorylation of the DNA-binding protein can alter various properties including protein dgradation, recruitment of co-activators, and DNA binding
Describe how the activity of nuclear hormone receptors is controlled, and how tamoxifen acts in breast cancer therapy
Estrogen binds to nuclear hormone receptors and activates proliferative cell types–this can e dangerous in cancer. Tamoxifen antagonizes estrogen by binding to estrogen receptors and preventing recruitment of HAT cofactors.
Describe how the amount of an activator/repressor can be regulated within the cell.
B-catenin: without Wnt signaling, the cytoplasmic pool of B-cat is targeted for degradation (Ub); however, with Wnt, B-cat is not phosphorylated which leads to an increase in the cytoplasmic pool of the protein. This allows some of the B-cat to move to the nucleus where it interacts with the TCF family of txn factors –> Wnt responsive genes
Describe a mechanism by which the DNA binding activity of a sequence specific DNA binding protein can be inhibited
The Id family member negatively regulate DNA binding by heterodimerizing with other HLH proteins through their HLH domains, but preventing DNA binding due to their lack of a basic domain. The relative abundance of these proteins is what dictates transcription or not
List a protein modification that can alter the activity of a sequence-specific DNA binding protein, and explain the mechanism by which the activity is altered
CREB (cyclic AMP response element-binding protein) - A series of events initiated by the binding of a ligand to a guanine nt-binding protein coupled receptor induces the phosphorylation of the CREB protein, which, while present on the DNA, is inactive to promote transcription unless phosphorylated. Once phosphorylated, the CREB protein recruits CBP, which has intrinsic HAT activity and recruits RNA Pol II leading to txn of a gene
Aside from transcriptional regulation, list at least 3 additional mechanisms to control levels of gene expression
- ) Control of mRNA export from the nucleus.
- ) Control of mRNA degradation
- ) Control of efficiency of translation
- ) Control of protein degradation
