33 Questions
Which of the following is true about GPCR proteins?
They have 7 transmembrane domains (TMDs)
What is the approximate number of GPCR family in humans?
800
Which of the following is NOT a role of GPCR proteins?
Sensing touch
What are some examples of ligands that can bind to GPCR proteins?
Lipids
Which of the following cannot be a research technique used to study GPCR proteins?
First messenger neurochemistry
Which of the following is incorrectly matched?
Rhodopsin - Venus flytrap domain
Which receptor class has a hormone receptor motif domain?
Secretin
Which technique was used to develop understanding of structure and receptor activation in proteins?
X-ray crystallography
Why is it more difficult to crystallize proteins in the active state with an agonist bound?
Agonist binding causes a conformational shift
What happens to the α-subunit's affinity for GDP and GTP upon ligand binding?
Affinity for GDP decreases, affinity for GTP increases
Which of the following is incorrect about G-Protein α Subunit Families?
Inhibitory - increases cAMP formation, activate or inhibit ion channels
Which of the following is NOT a function of the G-protein βγ subunit in signaling?
Activating PI3 kinase
Which GPCR receptor class is primarily involved in inhibiting action potential activity through the activation of GIRK K+ channels?
Gi Coupled GPCRs
Which of the following is a major transducer of Gi Coupled GPCRs?
GIRKs
What is the role of the βγ subunits in Gi Coupled G-protein signaling?
Inhibiting action potential via GIRK
Which of the following is true about GPCR modulation compared to ionotropic receptors?
GPCR modulation is slower than ionotropic receptors
Which of the following is NOT a factor affecting the time of action in GPCR signaling?
Ligand concentration
Which drug has the highest intrinsic efficacy among the given options?
Methadone
What is the formula for signal amplification in GPCR signaling?
S = ε[A.R]
Which enzyme phosphorylates the GPCR once the βγ subunits have dissociated?
GRK
What happens to the GPCR once it is phosphorylated by GRK?
It becomes a substrate for β-arrestin
Where does β-arrestin drag the phosphorylated GPCR?
Clathrin-coated pits
What happens to the GPCR once it is in the clathrin-coated pits?
It becomes a vesicle that is sent to the endosome
What are the possible fates of the GPCR in the endosome?
It may eventually return to the membrane, be hydrolysed, or may signal again from the endosome
What is the purpose of the intrinsic feedback process in GPCR regulation?
To lead to desensitization and tolerance
What is an example of GPCRs with highly conserved structures but vastly different physiological effects?
Adrenoreceptors
Which of the following is correctly matched?
Oxycodone - Moderate G-Protein Signal, Weak Arrestin Signal
What is the potential advantage of allosteric binding sites in terms of drug development?
Greater potential for selective drugs
What is the function of DREADDs?
Do not respond to muscarinic receptor agonists
Which GPCR is an algal motility photoreceptor cation conducting protein?
Channelrhodopsin (ChR2)
What is a way GPCR selectivity could be developed?
Receptor number and intrinsic efficacy of agonist
What is the function of Halorhodopsin (ChR2)?
Anion conducting
What are some factors affecting GPCR signaling?
Receptor number and downstream amplification
Test your knowledge on GPCRs, a large and diverse family of proteins with crucial roles in sensing extracellular signals. Learn about their structure, function, and significance as major drug targets. Discover how GPCRs play a role in sensory perception, neurotransmission, hormone regulation, and growth factors.
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