Transcription Flashcards
first four steps of polyadenylation
CPSF binds polyA signal
Cstf binds GU rich region / CFI&II bind polyA site
PAP binds
cleavage 10-35 nts downstream of polyA signal
what is significant about PAP?
needs no template and therefore polyA tail not encoded in genome.
what happens in polyadenylation after cleavage?
PAP adds AMP, cleaving pPi (slow)
PABII binds SHORT POLYA TAIL –> increases
after 200-250 residues PABII signals PAP to stop.
which exons are involved in the tra gene for males and females?
1 & 2 (stop codon) for males
1 & 3 for females
splicing of sxl?
3& 4 for females (tra 1 & 2 & Rbp1) promote polyadenylation in alternative splice site
3 & 5 for males
capping process
hydrolysis of terminal phosphate
5’end diphosphate attacks alpha phosphorous of GTP
5’5’ triphosphate link
N7 of terminal guanine methylated
how is the RNA of apoB changed?
cytidine deaminated to uridine by deaminase found only in small intestine, not in liver.
what is notable about transcription factors?
they have both DNA and transcription activation domains.
what are the key features of the TATA box?
25-35 base pairs upstream of start site
highly conserved in eukaryotes
what are the notable features of TFIIH?
9 subunits
helicase subunit hydrolyses ATP & unwinds DNA
protein kinase phosphorylates CTD of polymerase II
what are the notable features of TFIIH?
9 subunits
helicase subunit hydrolyses ATP & unwinds DNA
protein kinase phosphorylates CTD of polymerase II
What are the 4 steps on the splicing reaction?
exon 1 & 5’ end of intron - phosphodiester bond cleaved (by 2’OH of adenylate in branch site.
2’5’ P bond formed between A residues & 5’ terminal end of intron
3’OH of exon 1 attacks P bond between intron & exon 1
exon 1 & exon 2 joined, intron released as lariat.
where does U1 base pair to and what binds branch point site?
5’ splice junction
BBP & U2AF (then displaced by U2)
what is an snRNP & which two catalyse the first TE?
small nuclear RNA complexed with proteins
U2 & U6.
