Final answer:
The TATA box is the promoter region for RNA polymerase II that overlaps the transcription start point and is rich in thymine and adenine (T's and A's, often reading as TATAAAA). This sequence helps to unwind the DNA template for transcription initiation by RNA polymerase II.
Step-by-step explanation:
The promoter region for RNA polymerase II that overlaps the start point for transcription and is rich in C's or T's is known as the TATA box. The TATA box is a critical DNA sequence motif found within the promoter region, typical for eukaryotic protein-encoding genes, and is located approximately 25 to 35 bases upstream of the transcriptional start site. It consists of a series of thymine and adenine dinucleotides, usually represented as 'TATAAAA' on the coding strand. The thermostability of A-T bonds is notably low, which assists in the local unwinding of the DNA template to facilitate transcription initiation.
Binding of transcription factors to the TATA box initiates the formation of the transcription initiation complex. For instance, transcription factor IIB (TFIIB), TFIIE, TFIIF, and TFIIH, alongside TATA-binding protein (TBP) as part of TFIID, are involved in the recruitment of RNA polymerase II to the promoter. Once bound, RNA polymerase II is phosphorylated, which activates the initiation complex and aligns the enzyme for the start of transcription.