The TATA box is a core promoter sequence found in eukaryotic genes located about 25-30 base pairs upstream of the transcription start site. Its primary function is to serve as a binding site for the TATA-binding protein (TBP), a subunit of the transcription factor TFIID. This binding facilitates the recruitment of RNA polymerase II and other transcription factors, thereby initiating the assembly of the transcription pre-initiation complex. Without the TATA box, RNA polymerase II cannot efficiently locate the start site for transcription, making it essential for accurate gene expression regulation in eukaryotic cells.

Reference: Molecular Biology of the Cell, Alberts et al., 6th Edition.