The signal transduction of steroid hormone across cell is through :a)B...
Steroid hormones, being hydrophobic molecules, diffuse freely into all cells and act within the cell. Steroid hormones secreted by adrenal cortex, ovaries, and testes do not utilize the second messenger to exert their influence. Steroid hormones enter the cytoplasm of a target cell and bind with specific receptor proteins (mobile). Hormone-receptor complex than diffuses into the nucleus and activates specific genes to form a new protein. This protein carries out the specific response for a particular steroid hormone.
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The signal transduction of steroid hormone across cell is through :a)B...
Signal Transduction of Steroid Hormones:
Steroid hormones are lipid-soluble molecules that can easily cross the cell membrane. Their signal transduction involves the binding of the hormone to a cytoplasmic receptor, forming a hormone-receptor complex. This complex then translocates to the nucleus and binds to specific DNA sequences called hormone response elements (HREs) within the promoter region of target genes.
Process of Signal Transduction:
The signal transduction of steroid hormones can be summarized as follows:
1. Binding of Hormone to Cytoplasmic Receptor: Steroid hormones diffuse through the plasma membrane and bind to specific cytoplasmic receptors. These receptors are typically located in the cytoplasm or the nucleus.
2. Formation of Hormone-Receptor Complex: Upon hormone binding, the receptor undergoes a conformational change, leading to the formation of a hormone-receptor complex.
3. Translocation to the Nucleus: The hormone-receptor complex translocates to the nucleus, where it interacts with DNA.
4. Binding to Hormone Response Elements (HREs): Within the promoter region of target genes, there are specific DNA sequences known as hormone response elements (HREs). The hormone-receptor complex binds to these HREs.
5. Activation of Transcription: The binding of the hormone-receptor complex to HREs initiates the recruitment of coactivator proteins and other transcriptional regulatory proteins. This recruitment leads to the activation of transcription factors, which in turn regulate the transcription of target genes.
6. Gene Expression and Cellular Responses: The activated transcription factors bind to specific sequences on the DNA, promoting the transcription of target genes. This results in the synthesis of specific proteins and the generation of cellular responses.
Importance of Binding to Hormone Response Elements:
The binding of the hormone-receptor complex to hormone response elements (HREs) is crucial for the regulation of gene expression. HREs are specific DNA sequences that are recognized by the hormone-receptor complex. By binding to HREs, the hormone-receptor complex can directly influence the transcriptional activity of target genes, either by promoting or inhibiting their transcription.
Conclusion:
In conclusion, the signal transduction of steroid hormones involves the binding of the hormone to a cytoplasmic receptor. The hormone-receptor complex translocates to the nucleus and binds to specific DNA sequences called hormone response elements (HREs). This binding initiates the recruitment of coactivator proteins and transcriptional regulatory proteins, leading to the activation of transcription factors and the regulation of target gene expression.
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