So two important types of proteins you should be familiar with is transcription factor two D and transcription factor two B. Now, transcription factor 2D is itself a complex of many proteins, and one of the important proteins within the transcription factor 2D is known as the Tata binding protein or TBP. And this is the protein that actually binds to the sequence Tata found on the core promoter. Now, we also have the transcription factor to be, and this is the protein that is needed for the interaction to take place between the RNA polymerase, two protein found on the start side, and the task of binding protein. So that's why we need the transcription factor two B. So we see that the core promoter is where the majority of the proteins actually congregate when they actually bind.