35 Questions
What is the function of the Activation Function 1 (AF-1) surface?
Interacts with co-regulator proteins
Which type of receptors have a very large ligand binding pocket, allowing binding of differently sized ligands?
PPARg receptors
What is the difference in structure between liganded and unliganded receptors?
Liganded structures are more compact than the unliganded ones
How do most receptors bind to hormone response elements (HREs)?
As homo- or heterodimers to HREs composed typically of two core hexameric motifs
What is the characteristic feature of ER binding?
Binds palindromic HSE
What contributes to the specificity of binding of different steroid hormone nuclear receptors?
Specific base sequences interaction
What happens to the receptor after it binds the hormone?
Changes shape, sheds HSP and migrates into nucleus
Where are heterodimeric RXR NRs located under basal state?
Nucleus
What is the function of the leucine residues within the hydrophobic groove of the AF-2 surface?
Promote coactivator binding
Which motif is contained in the corepressors such as NCoR and interacts at the same hydrophobic AF2 surface with H12 in a different position?
LXXX(I/L)XXX(I/L)
What is the result of ligand (agonist) binding to RXR heterodimers?
Shift in H12 that promotes coactivator binding
What is the function of CBP/p300 in the context of histone modification?
Acetylate histones
What is the characteristic feature of steroid receptors when binding palindromic HSE?
Binds 2x AGAACA
What contributes to the specificity of binding of different Steroid hormone NRs?
Subdomain 1
What leads to the induction of nuclear transport for GR?
Time-dependent nuclear translocation of GFP-GR
Where are homodimeric NRs located under basal state?
Cytoplasm
What is the role of heat shock proteins (HSP) in regulating steroid receptors?
Inhibit transcription
What prevents heterodimeric RXR NRs from being active in the basal state?
Corepressor inhibition
What is the common basic structure shared by steroid hormones?
Cholesterol
What is the function of the peptide loop in the DNA binding Dimer formation region?
It participates in DBD dimerization and makes non-specific contacts with the DNA backbone
Where are C-terminal extensions (CTEs) found in some nuclear receptors like LRH-1 and GCNF located?
They make contacts with the minor groove of the DNA
In which part of the polypeptide chain are the highly conserved DNA-binding domains located?
Near the middle
What is the role of the second subdomain helix in the DNA binding process?
It makes non-specific contacts with the DNA backbone
What type of contacts do some nuclear receptors, like LRH-1 and GCNF, make with the minor groove of the DNA?
Base-specific contacts
Which residues on genomic response elements do the first subdomain residues of NR DBDs interact with?
Interact with the major elements of genomic response elements
What is represented as spheres in the Cartoon representation of folded GR DBD highlighting NR?
Zinc atoms
What is the structure of the ligand-binding domain (LBD) mainly composed of?
A three-layered, antiparallel helical sandwich
Which nuclear receptor contains an extra helix designed H29 in its overall structure?
PPARg
What is the poorly structured insertion between helices H1 and H3 found in the VDR?
Conserved b-turn
In which region of the LBD are the ligand-binding pockets located?
Buried within the bottom half of the LBD
What are the contacts with the ligand within the LBD described as?
Extensive and include different structural elements through the LBD
Which receptor has a very large ligand binding pocket, allowing binding of differently sized ligands?
PPARg
What is a characteristic difference between liganded and unliganded structures of receptors?
Unliganded structures are more compact
What is mainly hydrophobic and buried within the bottom half of the LBD?
Ligand-binding pocket
Which element creates a cavity, the ligand-binding pocket, within the LBD?
Central core layer of three helices
Test your knowledge of characteristic features of steroid hormone receptors, including their binding sequences, homodimer binding, contribution of subdomains, and interaction with DNA. This quiz covers the specificity of binding of different steroid hormone nuclear receptors and the ligands they interact with.
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