Final answer:
The cAMP response element is a specific nucleotide sequence that regulates gene transcription by allowing the binding of certain proteins. An example in eukaryotic cells is the CAAT box with the sequence 'GGCCAATCT'. cAMP activates PKA, initiating a phosphorylation cascade influencing both nuclear transcription and cytoplasmic responses.
Step-by-step explanation:
The cAMP response element is a specific nucleotide sequence to which certain proteins can bind, regulating gene transcription. Understanding this element is crucial to grasping how signals are transduced within cells to elicit a variety of responses, from gene expression changes to enzyme activation. An example of a response element is the CAAT box, which has a sequence of 'GGCCAATCT' and is essential for binding transcription factors in eukaryotic cells. Similarly, cAMP activates protein kinase A (PKA) and is the basis for a phosphorylation cascade effecting nuclear and cytoplasmic actions.