Final answer:
The conserved sequence located just upstream of the transcription initiation site in eukaryotic promoters is known as the TATA box, which is essential for the binding of transcription factors and RNA polymerase II to initiate gene transcription.
Step-by-step explanation:
The conserved sequence of approximately seven nucleotides located just upstream of the transcription initiation site in eukaryotic promoters is called a TATA box. The TATA box generally includes the consensus sequence 5'-TATAAA-3' on the coding strand and is typically situated about 25 to 35 bases upstream of the transcriptional start site (+1). The TATA box is crucial for the process of transcription initiation, as it serves as the binding site for the TATA-binding protein (TBP) and other transcription factors that form part of the transcription initiation complex. This complex enables the binding of RNA polymerase II to the promoter, initiating the transcription of genes.
Additionally, eukaryotic promoters may contain other important sequences such as the CAAT box (GGCCAATCT) and multiple GC-rich or octamer boxes (ATTTGCAT). These elements contribute to the efficiency and regulation of transcription by binding cellular factors that enhance the initiation process, particularly in genes that require a high level of expression. Unlike prokaryotic promoters which have the -10 and -35 consensus sequences, the TATA box plays a similar role in eukaryotes, helping to ensure precise initiation of transcription at the right location and time.