CAP in Lac operon is an example of: (A) Positive regulator, (B) Negative regulator, (C) Constitutive expression, (D) Attenuation
Answer is A. Catabolite activator protein(CAP) must bind to cAMP to activate transcription of the lac operon by RNA polymerase. CAP is a transcriptional activator with a ligand-binding domain at the N-terminus and a DNA-binding domain at the C-terminus.