Final answer:
Transcriptional regulators are proteins that bind to specific DNA sequences to regulate gene expression, responding to extracellular signals and regulating genes through the interaction with promoter sites. Enhancers and repressors also play roles, either boosting or suppressing gene transcription.
Step-by-step explanation:
Transcriptional regulators (TRs) are integral in the process of gene regulation in cells. Their action is complex in nature and the binding domain is highly specific for interaction with DNA. Each gene is regulated individually, but a single TR can coordinate multiple genes. While TRs often assemble into complexes, not all TRs have the same domain structure.
DNA-binding motifs within transcription factors recognize specific sequences in the major groove of the double helix. Each TR binds to specific DNA sequences called cis regulatory elements, which can be proximal or distal to the gene they regulate. These elements are critical for the communication between cells and their environment, involving signaling molecules like hormones and cytokines that ultimately influence gene expression.
The eukaryotic gene regulation mechanism by TRs includes positive regulation, where most genes are normally inactive and require the presence of activator proteins to initiate transcription. These activator proteins bind to promoter sites that can be located up to 1000 bases away from the gene they regulate requiring protein-protein interactions to activate the main gene.
Additionally, regulation at the transcription level may involve enhancers and repressors. Enhancers can increase transcription by looping back and interacting with a gene's promoter, while repressors can suppress transcription through their binding to regulatory regions.