Which statement about receptors is true?

Which statement about receptors is true?

• A. A signal can only bind one type of receptor
• B. Receptors can act as transcription factors
• C. All extracellular signals cannot diffuse across the cell membrane
• D. Two of the above

Answer: (B)

The statement that receptors can act as transcription factors is true because certain types of receptors function as transcription factors when they bind to their respective ligands. These receptors, typically located within the cell, can directly influence gene expression by interacting with DNA and regulating the transcription process. When a ligand binds to such a receptor, it can undergo a conformational change that allows it to bind to specific regions of the DNA, thereby either promoting or inhibiting the transcription of target genes. This role is particularly prominent in steroid hormone receptors, which move from the cytoplasm into the nucleus upon activation and bind to specific DNA sequences to modulate gene expression. Understanding this function is crucial in fields like pharmacology and biotechnology, where manipulating these pathways can lead to therapeutic advancements. The other statements do not hold universally true; for instance, not all signals are restricted to specific receptor types, and while some extracellular signals cannot cross cell membranes, others can, depending on their chemical nature.

The statement that receptors can act as transcription factors is true because certain types of receptors function as transcription factors when they bind to their respective ligands. These receptors, typically located within the cell, can directly influence gene expression by interacting with DNA and regulating the transcription process. When a ligand binds to such a receptor, it can undergo a conformational change that allows it to bind to specific regions of the DNA, thereby either promoting or inhibiting the transcription of target genes.

This role is particularly prominent in steroid hormone receptors, which move from the cytoplasm into the nucleus upon activation and bind to specific DNA sequences to modulate gene expression. Understanding this function is crucial in fields like pharmacology and biotechnology, where manipulating these pathways can lead to therapeutic advancements. The other statements do not hold universally true; for instance, not all signals are restricted to specific receptor types, and while some extracellular signals cannot cross cell membranes, others can, depending on their chemical nature.