Gluco-corticoid Receptor Protein
9.22.11
Case Study
• What is generalized
glucocorticoid resistance
syndrome?
• Go through the case
report. Pg 2
• HTA axis
cortisone
• Through the
DBD and LBD
of ER, and AP-2
sites
• Binding of
estrogen
dislodges the
HSP90
complex,
allows binding
to AP-2 site
Glucocorticoid Receptor (GR) (blue) binds to DNA (in
orange and tan) upon cortisone (in purple) binding
• Cortisone
found in both cytoplasm and nucleus of many
different kinds of cells
• Shown here as a dimer (vertical line separates)
• Two major types, α and β, both act as dimers
• LBD is the C-terminal Ligand Binding domain
• H helix is rearranged when cortisone binds
• cortisone’s binding affect s dimerization and binding
to additional transcriptional elements by exposing
hydrophobic surfaces
•Agonists and antagonists show differential
rearrangements of the H helix
•DBD is the N-terminal DNA binding domain
• binds to glucocorticoid responsive element (GRE) on DNA
•Initiatives downstream activation of transcription
•Assisted in transcriptional activation by other
transcriptional elements
H helix in GR modulates function of GR
H helix
• position is sensitive to
chemical nature of ligand and
type of GR (alpha or beta)
cortisone
• normally closed when GR
binds at LBD (top image)
•Cannot close, when
antagonists bind- this blocks
the action of the receptor
(bottom image)
Cortisone
antagonist
DNA binding domain in GR finds specific region
Recognition of GRE on
DBD mediated
through recognition
helix, and Zn(II) finger
domains
Dimer binds to DNA
Palindromic
recognition sequence
on DNA
PDB code 1hcq
Properties of GRα
• 96% sequence
homology in DBD
• 58% sequence
homology in LBD
• Size (RNA splicing
isoforms)
– GRα- Chromosome 6
(6q25.1)
Protein Structure α-HELIX
• Human glucocorticoid receptor
– pdbID 1M2Z
glucocortisone
dexamethasone
Protein Structure α-HELIX
• Human glucocorticoid receptor
– pdbID 1M2Z
glucocortisone
dexamethasone
Homodimer
12 alpha helices,
4 beta sheets
Secondary Structure
Homodimer
12 helices only
10 found by
program
4 beta sheets;
two on outside
and two at
interface
Secondary Structure
N  C Rainbow shows for each
molecule the N (blue) terminus to
the C (red) terminus
N termini (helix 1) on A and D
connected to the DNA binding
domain
C termini (helix 12) in A and D
involved in binding to GRIP and
others.
Helix 12, on GE binds the AF helix in
antiparallel +4+3 packing
• Mutation is R714 to N in of helix 10, wt R ion pairs w E662 of helix 8
• R mutated to N , E662 binds w. R704 of helix 9 (moves 0.4 nm)
• This switch releases helix 10,
• Mutation is R714 to N in of helix 10 released, causes Y735 rotamer and disrupts
bind AF-2 through helix 12
Ligand Binding Domain Switch
•
•
•
•
1NHZ Glucocorticoid with antagonist
1P93 Glucocorticoid with agonist
3H52 active/passive forms with antagonist
Mouse glucocorticoid receptor
– 3MNE (single mutant)
– 3MNO (double mutant)
– 3MNP (triple mutant)