How do steroid hormones typically signal target cells?

How do steroid hormones typically signal target cells?

• A. By binding to cell surface receptors.
• B. By passing through the cell membrane to bind to intracellular receptors.
• C. By activating G-protein coupled receptors.
• D. By initiating a second messenger cascade.

Answer: (B)

Steroid hormones typically signal target cells by passing through the cell membrane and binding to intracellular receptors. This process is fundamentally different from how many other hormones operate. Steroid hormones are lipophilic, which allows them to diffuse easily through the lipid bilayer of the cell membrane. Once inside the cell, they bind to specific intracellular receptors, which then undergo a conformational change. This binding of the steroid hormone to its receptor activates the receptor and often leads to the translocation of the hormone-receptor complex to the nucleus. In the nucleus, the complex interacts with specific DNA sequences to regulate the transcription of target genes, ultimately resulting in defined physiological responses. This mechanism is crucial because it allows for a direct and potentially long-lasting effect on cellular function through the alteration of gene expression. On the other hand, options related to binding cell surface receptors or activating G-protein coupled receptors typically refer to peptide hormones or other signaling molecules that cannot easily cross the membrane and therefore must signal via extracellular receptors, leading to second messenger cascades. These processes are distinct from the direct genomic action exercised by steroid hormones.

Steroid hormones typically signal target cells by passing through the cell membrane and binding to intracellular receptors. This process is fundamentally different from how many other hormones operate. Steroid hormones are lipophilic, which allows them to diffuse easily through the lipid bilayer of the cell membrane. Once inside the cell, they bind to specific intracellular receptors, which then undergo a conformational change.

This binding of the steroid hormone to its receptor activates the receptor and often leads to the translocation of the hormone-receptor complex to the nucleus. In the nucleus, the complex interacts with specific DNA sequences to regulate the transcription of target genes, ultimately resulting in defined physiological responses. This mechanism is crucial because it allows for a direct and potentially long-lasting effect on cellular function through the alteration of gene expression.

On the other hand, options related to binding cell surface receptors or activating G-protein coupled receptors typically refer to peptide hormones or other signaling molecules that cannot easily cross the membrane and therefore must signal via extracellular receptors, leading to second messenger cascades. These processes are distinct from the direct genomic action exercised by steroid hormones.