Multiple Choice
Steroid hormones signaling through binding….
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14. Cell Signaling
Intracellular messnegers: Hormones and Nitric Oxide
Multiple Choice
The mechanism by which testosterone alters cell function is by:
A
Binding a receptor tyrosine kinase on the cell surface to trigger a MAPK phosphorylation cascade without directly altering transcription
B
Diffusing through the plasma membrane and binding an intracellular androgen receptor that acts as a transcription factor to regulate gene expression
C
Binding a cell-surface receptor that activates adenylate cyclase to increase cAMP and rapidly phosphorylate target proteins
D
Stimulating nitric oxide synthase to generate nitric oxide that activates soluble guanylyl cyclase and increases cGMP
Verified step by step guidance1
Step 1: Understand the nature of testosterone as a steroid hormone. Steroid hormones are typically lipophilic (fat-soluble), allowing them to diffuse through the plasma membrane rather than binding to cell surface receptors.
Step 2: Recognize that once inside the cell, testosterone binds to specific intracellular receptors called androgen receptors. These receptors are located in the cytoplasm or nucleus and function as transcription factors.
Step 3: Upon binding testosterone, the androgen receptor undergoes a conformational change, allowing it to translocate into the nucleus if it is not already there.
Step 4: Inside the nucleus, the testosterone-receptor complex binds to specific DNA sequences known as hormone response elements, regulating the transcription of target genes and thereby altering gene expression.
Step 5: Contrast this mechanism with other signaling pathways such as receptor tyrosine kinases, adenylate cyclase activation, or nitric oxide signaling, which involve cell surface receptors and second messengers rather than direct gene regulation by intracellular receptors.
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