Multiple Choice
Under what condition will a target cell always respond quickly to an extracellular signal?
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16. The Endocrine System
Membrane Bound Receptors and Secondary Messengers
Multiple Choice
What is the role of G proteins in GPCR signaling?
A
Catalyzing DNA synthesis.
B
Initiating apoptosis.
C
Transcription of mRNA.
D
Activating downstream effectors.
Verified step by step guidance1
Understand that GPCR stands for G Protein-Coupled Receptor, which is a large family of cell surface receptors that respond to various external signals.
Recognize that G proteins are intracellular proteins that bind guanosine triphosphate (GTP) and guanosine diphosphate (GDP) and are involved in transmitting signals from GPCRs to other parts of the cell.
When a ligand binds to a GPCR, it causes a conformational change in the receptor, which then activates the associated G protein by facilitating the exchange of GDP for GTP on the G protein.
The activated G protein, now bound to GTP, dissociates into its subunits (usually the alpha subunit and the beta-gamma dimer), which then interact with various downstream effectors such as enzymes or ion channels, leading to a cellular response.
The role of G proteins in GPCR signaling is to act as molecular switches that activate downstream effectors, thereby propagating the signal initiated by the ligand binding to the GPCR.
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