Transcription factors:
- Proteins that interact with specific DNA sequences called regulatory elements (enhancers and promoters) to either activate or repress gene transcription.
- They can be turned on or off by various internal and external signals, ensuring precise control over which genes are expressed and when.
Epigenetic modifications:
- Chemical modifications to DNA and histone proteins that influence the accessibility of genes to transcription factors, thereby regulating gene expression.
- Mechanisms such as DNA methylation and histone acetylation/methylation can alter the chromatin structure and make genes either more accessible (active) or less accessible (repressed).
mRNA processing:
- After transcription, messenger RNA (mRNA) undergoes various processing steps before it can serve as a template for protein synthesis.
- These steps include modifications such as splicing (removal of introns and joining of exons) and the addition of a 5' cap and a 3' poly-A tail.
- These modifications stabilize the mRNA, promote its export from the nucleus to the cytoplasm, and increase its efficiency in translation.
Translational control:
- Several mechanisms can regulate the translation of mRNA into protein inside the cytoplasm, including:
- Ribosome binding: Control over the binding of ribosomes to mRNA for protein synthesis.
- Translational factors: Proteins involved in the translation process can be regulated to influence the efficiency or fidelity of protein production.
- MicroRNAs: Small non-coding RNAs that bind to specific mRNA sequences and prevent their translation or target them for degradation.
These regulatory mechanisms ensure that protein production in the cytoplasm faithfully reflects the genetic information encoded in the DNA within the nucleus. Disturbances in these regulations can lead to abnormalities in gene expression and contribute to various diseases, including cancer, developmental disorders, and metabolic diseases.
