17 Questions
What is the function of the α subunit of the Trimeric G Protein?
Enhancing GTP hydrolysis
Which role do RGS proteins play in the GTPase cycle of Trimeric G Proteins?
Acting as GAPs for α-subunit-specific GTPase activation
How does a Trimeric G Protein become inactive?
By binding to GDP
Which component of the Trimeric G Protein has lipid molecules attached to help bind to the plasma membrane?
γ subunit
What is the function of Guanine Exchange Factors (GEFs) in the GTPase cycle of Trimeric G Proteins?
Enhancing GTP binding
How do GAPs regulate Trimeric G Proteins?
Enhancing GTP hydrolysis
What is the role of a Guanine Exchange Factor (GEF) in GPCR signaling?
It activates the G protein by inducing the release of GDP and binding of GTP.
How many subunits make up a Trimeric G protein?
Three subunits
What happens to the α-subunit of a Trimeric G protein in its unstimulated state?
It binds to GDP and is inactive.
Which part of the Trimeric G protein binds to GDP in its inactive state?
α-subunit
How does the ligand binding to a GPCR affect the associated Trimeric G protein?
It induces the α-subunit to release GDP and bind GTP.
Where does the ligand bind in a typical Trimeric GPCR structure?
Near the N terminus
What is the role of Guanine nucleotide-dissociation inhibitors (GDIs) in G protein signaling?
Prevent GDP/GTP exchange
How do Regulatory proteins of G protein Signalling (RGS) contribute to G protein responses?
Act as α-subunit specific GAPs to shut off G protein-mediated responses
How many RGS proteins are encoded in the human genome?
25
Which of the following families of trimeric G proteins are involved in GPCR signaling pathways?
4 families
What is the signaling effect of cAMP activation by Gs on plasma membrane-bound enzymes?
Activation of CREB transcription factor
Test your knowledge on the signaling mechanism of trimeric G proteins, including the conformational changes in the α-subunit, GTPase activity, and interactions with target proteins. Explore how trimeric G proteins relay signals in cells.
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