Nuclear Receptors Flashcards
where are nuclear receptors present?
in soluble phase of cell
when do steroid receptors become mobile?
in presence of their ligand
can translocate from cytoplasm nucleus
what are the nuclear receptor family known as?
ligand activated transcription factors
transduce signals by modifying gene transcription
what do many nuclear receptors act as?
lipid sensors
many illnesses associated with malfunctioning of the nuclear receptor system include what?
- inflammation
- cancer
- diabetes
- cardiovascular disease
- obesity
- reproductive disorders
class I receptors
receptors for steroid hormones
receptors:
- glucocorticoids
- mineralocorticoids
- oestrogen
- progesterone
- androgen
for class I receptors, where are they located in the absence of their ligand?
in cytoplasm complexed with heat shock proteins
what do class I receptors form?
homodimers
what can class I receptors do following translocation to the nucleus?
- transactivate
- transpress genes
by binding to pos/neg hormone response elements
what do class II receptors include?
- peroxisome proliferator-activated receptor (PPAR)
- liver oxysterol receptor - cholesterol sensor (LXR)
- farnesoid (bile acid) receptor FXR
- xenobiotic receptor (SXR)
what do class II receptors operate as?
heterodimers with retinoid receptors (RXR)
mediate positive feedback effects
what is the third group of nuclear receptors?
subgroup of class II
form heterodimers with RXR
inc: thyroid hormone receptor, vitamin D receptor, retinoic acid receptor
what does the N-terminal domain display?
most heterogeneity
harbous AF1 (activation function 1) site that binds to other cell-specific TF
what is the core domain?
structure responsible for DNA recognition + binding
what does the core domain comprise of?
2 zinc fingers cysteine rich loops in AA chain
held in conformation by zinc ions
