Catabolite activator protein (CAP)

Definition

Catabolite Activator Protein (CAP) is a regulatory protein in prokaryotes that binds to DNA and stimulates transcription. It is activated by cyclic AMP (cAMP), which allows it to enhance the expression of certain genes, particularly those involved in catabolism.

5 Must Know Facts For Your Next Test

1. CAP functions by binding to specific sites on DNA when cAMP levels are high.
2. It is crucial for the regulation of the lac operon in E. coli.
3. CAP-cAMP complex formation is essential for initiating transcription of certain operons.
4. The presence of glucose inhibits cAMP production, thereby reducing CAP activity.
5. CAP is an example of positive control in gene regulation, enhancing the transcription rate of target genes.

Review Questions

• How does Catabolite Activator Protein (CAP) influence gene expression?
• What role does cyclic AMP (cAMP) play in the function of CAP?
• Why does the presence of glucose affect CAP activity?

Related terms

lac operon: A set of genes involved in lactose metabolism regulated by CAP and other proteins.

cyclic AMP (cAMP): A molecule that acts as a secondary messenger and activates CAP.

positive control: A regulatory mechanism where a protein increases the rate of transcription of a gene or set of genes.