Regulation of Gene Expression Flashcards
Points of regulation is eukaryotic gene expression
transcription transport of RNA and ribosomes once in cytosol translation compartmentalisation and secretion
Regulation in transcription
mRNA initiate and terminate
post-transcriptional regulation (cap and poly(A)) - degradation or spliced
Regulation once in cytosol
degradation
sequest into inactive form, allow rapid translation
Regulaiton in translation
degradation of preliminary protein
processing (eg. folding)
Regulation in compartmentalisation and secretion
where the protein is transported to
Importance of transcriptional regulation
for most eukaryotic genes, transcriptional control prevents formation of any unwanted intermediates
Core mechanisms of transcriptional regulation
- binding of sequence-specific transcription factors to DNA
2. control of DNA packaging and chromatin structure
What are most aukaryotic genes controlled by?
complex cis-acting sequences within their promoters
these are recognised by TFs, which contain both DNA-binding and transactivation domains
How do TFs recognise discrete DNA sequence patterns
‘read out’ sequence-specific info from major and minor grooves in DNA
most TFs interact with bases exposed in the major groove - bigger and more molecular features visible
Examples of DNA-binding motifs of TFs
helix-turn-helix
leucine zipper
helix-loop-helix
What do most TFs function as? and why?
dimers, increases binding affinity and specificity
can be hetero/homodimers
How is eDNA packaged and condensed into chromatin?
DNA-binding TFs recruit other regulators: co-activators and co-repressors
then packaged and condensed
Importance of chromatin formation
modification of local chromatin structure is central to transcriptional regulation
requires DNA interation with histone proteins
What are histone proteins?
small, basic molecules with many C-terminal lysines
What is a nucleosome?
structural units which histones have packaged and ordered DNA to form
lowest level of higher-order DNA structure in chromatin
