University of Central Florida (UCF) PCB4524 Molecular Biology II Practice Exam 1

Transcription factors are essential proteins that regulate gene expression in eukaryotic cells by binding to specific DNA sequences. For these factors to function properly, they often require the phosphorylation and binding of other proteins. This is because phosphorylation can change the conformation of a transcription factor, influencing its activity, stability, and interaction with other components of the transcription machinery, such as RNA polymerase and co-activators or co-repressors.

Additionally, many transcription factors work in complexes, meaning that they must interact with other proteins to mediate the initiation and regulation of transcription effectively. These interactions can include things like binding to enhancers or promoters, forming multi-protein complexes, or necessitating post-translational modifications, such as phosphorylation. Thus, the requirement for these modifications and interactions is crucial for the correct functioning of transcription factors in the complex environment of eukaryotic cells.

The other options do not address the immediate regulatory mechanisms that influence transcription factor activity as directly as the need for phosphorylation and protein interactions does. For instance, while a DNA template is necessary for transcription to occur, it does not specifically impact the activation or modulation of transcription factors. Similarly, high levels of ATP and low cellular pH do not relate to the specific requirements for