GPCR Flashcards
What is the structural components of GPCR
receptor, G protein, effector
Which receptor formoterol targets at?
It is B2 adrenergic Gas agonist (anti-asthma)
Which receptor clonidine targets at?
It is Gi agonist
Which receptor phenylephrine targets at?
It is a1 adrenergic Gq agonist (nasal decongestant )
What is the role of phosphodiesterase (PDE)?
breakdown cAMP/cGMP (depends on its subtype)
Describe transducin signalling pathway
- Photon binds to rhodopsin > conformational change
- Rhodopsin activates transducin (Gat)
- Transducin activates PDE V
- PDE V degrades cGMP
- Drop in cGMP inactivates Na+/Ca++ channel
- Rod cell hyperpolarization & send signal to brain
- Drop in Ca activates cytosolic guanylyl cyclase (increases cGMP)
- re-open Na+/Ca++ ion channel
- Photoreceptor signalling starts again
What happen when Gaq is activated
Phospholipase C is activated
What happen when PLC activated?
breakdown Phosphatidylinositol-4,5-bisphosphate (PIP2) into Diacyclgrlcerol (DAG) & Inositol 1,4,5-Triphosphate (IP3)
What is role of IP3
Activate Ca++ ion channel on ER to release Ca++, Ca++ binds to Calmodulin for signalling response
What does DAG do?
Activate prot. kinase C tgt w Ca++
Types of GPCR regulation
Ligand removal, desensitisation
Steps of desensitization
Uncoupling , Internalisation , down-regulation
Role of GRK
Phosphorylate GPCR , allow arrestin to bind for desensitisation and internalisation Or down-regulation (breakdown receptor)
types of desentization
Homologous , heterologous
What is homologous desensitisation?
GPCR inactivated by GRK phosphorylation, arrestin binds to it
What is heterologous desensitisation
Phosphorylation by PKA,PKC inactivation
Tm for osteoporosis?
Calcitriol (VDR agoinst), Raloxifene (ER agonist)
What is the use of Mifepristone
Progesterone receptor antagonist, induce abortion
Glucocorticoids for?
GR agonist, anti-inflammatory
Drug for prostate cancer?
Apalutamide, AR antagonist
Drug for breast cancer?
Tamoxifen , PR antagonist
Tm for Type-II diabetes mellitus
Rosiglitazone (PPARy agonist)
Tm for acne (topical)
Tretinoin (RAR agonist)
Modes of nuclear receptor activation
- Genomic, Tethered, non-genomic, ligand-independent
Type of nuclear receptor
Class I, hybrid, Class II
Diff btw Class I & II nuclear receptor
- Class I found in cytoplasm, II in nucleus
- I operates as homodimers, II as heterodimers
- I high affinity , II low affinity
Examples of Class II nuclear receptors
peroxisome proliferator-activated receptor (PPAR), Aryl hydrocarbon receptor (AhRe)
Thyroid receptor is which type of nuclear receptor?
Hybrid receptor
Exp of Class I steroid receptor
GR, ER, MR, PR ,AR
Structure of nuclear receptor
Ligand-binding domain, DNA-binding domain, Transcription-activating domain
PPAR full form?
Peroxisome proliferator-activated receptor
