Transcription III

Question 1

6 Ways to Regulate TF

Answer 1

Synthesis – target mRNA for degradation (AGO)
Access to DNA – euchromatin vs heterochromatin
Post-translational modifications – phosphorylation
Ligand Binding
Cellular Localization – cytoplasm vs nucleus
Availability of Co-activators

Question 2

Nuclear Receptors Domains

Answer 2

1) N-terminal Regulatory Domain (AF-1)
- independent of ligand
2) DNA-Binding Domain (2 Zinc Fingers bind to HRE)
3) Hinge Region
4) Ligand Binding Domain (AF-2 – dependent on ligand)
- dimerization + co-activators
5) C-terminal Domain

Question 3

Class I

Answer 3

Steroid Receptor (homodimer)
- receptor in cytoplasm bound to inhibitor (HSP)
- activate by steroid hormones –> translocate to nucleus
- bind to HRE = inverted repeats separated by 3 nts

= tissue development

Question 4

Class I Receptors as Research Tools

Answer 4

Cre-recombinase = delete specific genes
Tamoxifen = remove HSP
- receptor enter nucleus at specific time

Question 5

Class II

Answer 5

RXR Heterodimers
- receptor bound to gene in off state
- activate by metabolite/ligand passively enter nucleus
- bind as direct repeats separated by variable #of nts

= processing vitamins

Question 6

Class II Function

Answer 6

switching genes from off –> on
co-repressor –> add ligand = co-activator

Question 7

Class II in Development

Answer 7

Retinoic Acid
- without = co-repressor of Hox genes
- with = co-activator of Hox genes
—> needed in developmental processes (eyes/forelimbs)

Question 8

Class III and IV

Answer 8

Dimeric Orphan Receptor
- homodimers + direct repeats

Monomeric Orphan Receptors

Question 9

Nuclear Receptors in Cancer

Answer 9

diabetes, obesity, fibrosis, inflammation, angiogenesis