What is the function of the CAAT box in gene transcription?

The CAAT box functions primarily as a nucleotide consensus sequence located upstream of the transcription site in eukaryotic genes. This sequence is crucial for the binding of transcription factors that facilitate the initiation of transcription by RNA polymerase. By providing a specific site for these proteins to attach, the CAAT box helps in the effective regulation of gene expression, enhancing the transcriptional activity of the associated gene.

While the other choices mention mechanisms relevant to gene function, they do not accurately describe the role of the CAAT box in transcription. For instance, it does not act as a termination signal nor does it serve as a starting codon. Additionally, it is not involved in post-transcriptional modifications, which occur after the transcription process is complete. Therefore, the role of the CAAT box is specifically related to its location and function in the regulation of transcription initiation.