What role do activator proteins play in positive regulation of the Lac operon?

Activator proteins are crucial for the positive regulation of the Lac operon, as they enhance the transcription of genes associated with lactose metabolism. Their primary role is to bind to specific sites on the DNA known as enhancer regions or activator binding sites, which are often located near the promoter regions of the operon.

When activator proteins bind to these sites, they facilitate the recruitment of RNA polymerase (RNAP) to the promoter. This interaction is essential for the initiation of transcription, allowing RNAP to efficiently bind to the DNA and start the process of synthesizing RNA from the operon's genes. This leads to increased expression of the genes that are necessary for lactose uptake and utilization.

In this context, activator proteins play a pivotal role in ensuring that the genes for lactose metabolism are expressed when lactose is available, linking environmental cues directly to the genetic machinery of the cell. Therefore, the correct answer reflects the function of activator proteins in promoting transcription through the recruitment of RNAP to the promoter.