CST Guide:

Section I: Research Areas
chapter 01: GENE EXPRESSION, EPIGENETICS, AND NUCLEAR FUNCTION
Translational Control: Regulation of elF2
PTEN
Salubrinal
ATF-4, CHOP, mRNA
Translation
α
GDP
Apoptosis, Changes in
Metabolism & Redox Status
SirT1
eIF2B
eIF2 γ
Akt
Growth Factors,
ER Stress,
Viral Infection
dsRNA
PKR
GADD34
eIF2B
β
Unfolded Protein
Response, Hypoxia
PKR
PP1
CreP
eIF5
PERK
PERK
PP1
SirT1
Global Translation Off
40S
eIF3
eIF5
BiP
α
GDP
Glucose Deprivation,
UV Light, Amino Acid
Starvation
α
GDP
GDP
α
GTP
GCN2
GCN2
eIF2 γ
eIF2 γ
eIF2 γ
β
β
β
GTP
eIF2
Met-tRNAi
Ternary
Complex
43S
GTP
Global Translation On
eIF5
HRI
eIF5
Met-tRNAi
eIF1
eIF1A
Heme Deficiency,
Oxidative Stress
HRI
NCK
eIF2B
GSK-3β
Growth Factors,
Hormones, etc.
The eIF2 initiation complex integrates a diverse array of stress-related signals to regulate both global and specific mRNA translation. Under permissive conditions, eIF2 binds
GTP and Met-tRNAi to form the ternary complex (TC), which then associates with the 40S ribosomal subunit, eIF1, eIF1A, eIF5, and eIF3 to form the 43S pre-initiation complex
(PIC). The 43S PIC scans the mRNA UTR for an AUG start codon. Upon AUG recognition, eIF2 hydrolyzes GTP to GDP with the help of the GTPase activating protein eIF5
and dissociates from the mRNA, permitting the binding of the 60S ribosomal subunit and elongation of the polypeptide chain. eIF2 remains bound to GDP in the presence of
eIF5 acting as a GDI. To permit another round of initiation, eIF2B must act as both a GDI displacement factor (GDF) and a guanine exchange factor (GEF) to allow exchange of
GDP for GTP on eIF2. This step is tightly regulated, and phosphorylation of eIF2α by a diverse family of four stress activated kinases—PKR (dsRNA), PERK (ER stress), GCN2
(amino acid starvation), and HRI (heme deficiency)—prevents nucleotide exchange by causing eIF2 to act as a dominant negative complex to sequester eIF2B. The resulting
increase in eIF2α-GDP limits the availability of the ternary complex and causes a decrease in global protein synthesis and an enhancement of the translation of specific stressrelated
mRNA transcripts, such as the transcription factors ATF-4 and CHOP.
Select Reviews:
Hinnebusch, A.G. (2011) Microbiol. Mol. Biol. Rev. 75, 434–467. • Raven, J.F. and Koromilas, A.E. (2008) Cell Cycle 7, 1146–1150. • Schmitt, E., Naveau, M., and
Mechulam, Y. (2010) FEBS Lett. 584, 405–412. • Stolboushkina, E.A. and Garber, M.B. (2011) Biochemistry 76, 283–294. • Wek, R.C., Jiang, H.Y., and Anthony, T.G.
(2006) Biochem. Soc. Trans. 34, 7–11.
Nuclear Receptors
The nuclear receptor superfamily are ligand-activated transcription factors that play diverse roles in cell
differentiation/development, proliferation, and metabolism and are associated with numerous pathologies
such as cancer, cardiovascular disease, inflammation, and reproductive abnormalities. Members
of this family contain an N-terminal transactivation domain, a highly conserved central region zinc-finger
DNA binding domain, and a C-terminal ligand-binding domain. Ligand binding to its correlate nuclear
receptor results in transactivation of specific genes within a target tissue.
In addition to ligand binding, nuclear receptor activity can be modulated through the action of numerous
growth factor and cytokine signaling cascades that result in receptor phosphorylation or other
post-translational modifications, typically within the N-terminal transactivation domain. For example,
the estrogen receptor is phosphorylated on multiple serine residues that affect receptor activity. Ser118
may be the substrate of the transcription regulatory kinase CDK7, whereas Ser167 may be phosphorylated
by p90RSK and Akt. Phosphorylation of Ser167 may confer resistance to tamoxifen in breast
cancer patients.
Type I Nuclear Receptors
Type I nuclear receptors, also called steroid receptors, include the estrogen receptor, androgen
receptor, progesterone receptor, mineralocorticoid receptor, and glucocorticoid receptor. Steroid
hormone ligands for this subgroup of receptors travel from their respective endocrine gland through
the bloodstream bound to steroid binding globulin. Some type I nuclear receptors are activated, in part,
upon binding their respective ligand in the cytoplasmic compartment. The ligand-receptor complex dissociates
from HSP90 and enters the nucleus where it homodimerizes and binds to hormone response
elements within the promoter of a target gene. The receptor transactivation domain is responsible for
interaction at the promoter with co-activators such as acetyltransferases and the general transcription
machinery, resulting in transcriptional activation.
Androgen receptor, a type I nuclear receptor, plays a crucial role in several
stages of male development and the progression of prostate cancer.
A
Androgen Receptor (D6F11) XP ® Rabbit mAb #5153: IHC analysis of paraffin-embedded human prostate carcinoma (A) using #5153.
Confocal IF analysis of LNCaP (positive) (B) and DU 145 (negative) (C) cells using #5153 (green). Actin filaments have been labeled with
DY-554 phalloidin (red).
Dexamethasone treatment results in translocation of the glucocorticoid
receptor to the nucleus, where it associates with response elements within
glucocorticoid-responsive genes.
A
B
B
C
C
Commonly Studied
Nuclear Receptor
Targets
These protein targets represent key
nodes within nuclear receptor signaling
pathways and are commonly studied
in nuclear receptor research. Primary
antibodies, antibody conjugates, and
antibody sampler kits containing these
targets are available from CST.
Listing as of September 2014. See our
website for current product information.
M Monoclonal Antibody
P Polyclonal Antibody
Target M P
AhR
•
Androgen Receptor • •
Aromatase
•
COUP-TF1 •
COUP-TF2 •
Estrogen Receptor-α •
Phospho-Estrogen •
Receptor-α (Ser104/Ser106)
Phospho-Estrogen •
Receptor-α (Ser118)
Phospho-Estrogen •
Receptor-α (Ser167)
ERRα
•
Glucocorticoid Receptor •
Phospho-Glucocorticoid •
Receptor (Ser211)
NRBF-2
• •
Nur77
•
Phospho-Nur77 (Ser351) •
PHB2
• •
PPARγ
• •
Progesterone Receptor •
Phospho-Progesterone •
Receptor (Ser190)
Phospho-Progesterone •
Receptor (Ser294)
Phospho-Progesterone •
Receptor (Ser345)
Progesterone Receptor A/B • •
Progesterone Receptor B • •
RARα
•
RARγ
•
Rev-Erba •
Phospho-Rev-erba •
(Ser55/59)
RXR-α
• •
RXRβ
•
RXRγ
•
STF-1
•
Vitamin D3 Receptor •
© 2002–2015 Cell Signaling Technology, Inc. • We would like to thank Rachel Wolfson and Prof. David Sabatini, Whitehead Institute for Biomedical Research, MIT, Cambridge, MA, for reviewing this diagram.
38 For Research Use Only. Not For Use in Diagnostic Procedures. See pages 302 & 303 for Pathway Diagrams, Application, and Reactivity keys.
Glucocorticoid Receptor (D6H2L) XP ® Rabbit mAb #12041: IHC analysis of paraffin-embedded human prostate carcinoma (A) using
#12041. Confocal IF analysis of HeLa cells, grown in phenol red-free media containing 5% charcoal-stripped FBS for 2 d and either untreated
(B) or treated with dexamethasone (100 nM, 2 hr) (C), using #12041 (green). Actin filaments were labeled with DY-554 phalloidin (red).
www.cellsignal.com/cstnuclear 39