5. transcription Flashcards
(33 cards)
gene expression
the process by which information from a gene is used in the synthesis of a functional product
main types of non-coding RNA
- Protein translation: ribosomal (rRNA), transfer (tRNA)
- RNA processing: small nuclear (snRNA), small nucleolar (snoRNA)
- regulatory: micro (miRNA), long non-coding (lncRNA)
importance of control of gene expression
- development and specialisation
- prevention of cancer
- adaption to environment
controlled points of gene expression
transcription
- measured by RNA-seq and qPCR
Co-transcription/mRNA
- alternative splicing
Post-transcription
- miRNAs
Post-translation
RNA pol II subunits
called Rpb#
- catalytic subunits (Rpb1 & Rpb2) p
main CTD residues to get phosphorylated
- Ser 2 and Ser 5
Phosphorylation and de-phosphorylation enzymes
kinases - add phosphate group
phosphatase - remove phosphate group
RNA pol II needs help
- recognising start (TSS or core promoter) or end gene on its own
- binding DNA
- remodelling histones
writer proteins
Add histone tail modifications
eraser proteins
remove histone tail modifications
reader proteins
recognises histone tail modifications
stages of transcription
- pol II recruitment
- initiation and early elongation
- productive elongation
- termination
pre-mRNA
- virtual molecule
- processing is co-transcriptional
Transcription start site (TSS)
- the nucleotide where transcription starts at the 5’ nucleotide at the transcript
Core promoter (CP)
- Where RNA Pol II is recruited to
- close to/overlaps TSS
Cis-regulatory elements (CRE)
- short DNA sequences (motifs) involved in transcriptional regulation
- incudes enhancers and silencers
- protein binding sites
Transcription activators
transcription factors that recognise and bind a specific enhancer to initiate/increase transcription of target genes
two domains
- dna binding domain (DBD)
- Activator domain (AD)
transcription repressors
transcription factors that recognise and bind specific silencer to prevent/repress transcription of target genes
two domains
- DNA binding domain (DBD)
- Repressor domain
DNA activator/repressor binding domain
-Binds a silencer/enhancer
- holds repression/activation domain in promoter vicinity
Activator activation domain
protein-protein interactions
- other activators (complex)
- co-activators
Repressor repression domain
protein-protein interactions
- co-repressors
not present in every repressor
stages of initiation and early elongation
-PIC formation/RNA pol II recruitment
- initiation
- abortive elongation
- promoter clearance
spliceosome
is an ATP dependant complex of splicing factors that catalyzes mRNA splicing
CTD phosphorylation during transcription
- RNA pol recruitment : not phosphorylated
- initiation and early initiation: Ser 5 P
- Productive elongation : Ser 2 P, Ser 5 P
- Termination: Both P removed -> no P
