Transcription: Advanced Look --> 2.) Poll II (RNA Polymerase II)

RNA Polymerase II (Poll II) is the complex responsible for reading the DNA template and creating a complementary mRNA copy. In order for Poll II to begin this process, several general transcription factors must first help to position and activate the Poll II complex. Clicking on each of the thumbnail images will bring up a larger, labeled version of the described scene.

To see the Quicktime movie for the following sequence of images, click here.

	Two smaller general transcription factors are shown coming into view: TFIIA (orange) and TFIIB (red).
	TFIIA binds to the TATA-box near TFIID.
	TFIIB approaches the TATA-box. The Poll II complex is being assembled in the distance.
	TFIIB binds to the TATA-box and TFIID. It is thought to help the Poll II complex bind correctly.
	The Poll II complex has been assembled and is approaching the start site for transcription.
	Aided by the general transcription factors already in place, Poll II binds to the DNA strand at the start site for transcription. TFIIE is show approaching from the right.
	Additional factors must still bind to the complex in order to start transcription. Here, TFIIE has already bound (olive green) and TFIIH (red) is preparing to do the same.
	Once all of the general transcription factors are bound, energy, in the form of ATP (blue/pink), is needed to activate the Poll II complex.

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