Eukaryotic mRNA Processing Flashcards
Recruitment of Capping Enzymes
phosphorylating serine5 recruits capping enzymes
Recruitment of Cleavage Factors
recruiting occurs through phosphorylation of serine2 on CTD, allows mRNA splicing and cleavage
Poly-A Polymerase (PAP)
recruited by serine2 phosphorylation, creates the Poly-A tail
Poly-A Binding Proteins (PABP)
via CTD tail phosphorylation on serine 2, allows poly A tail to be manufactured
5’ Cap
important for protection from degradation, transport out of the nucleus, recognition for translation machinery
added to the 5’ end of mRNA transcripts as they are being transcribed, created by factors recruited by phosphorylated Serine5
actually a guanine that is reversed and has a methyl added to it (methylguanine cap)
Poly-A Tail Addition
important for protection from degradation and transport out of the nucleus
hnRNA
longer than mRNA, the primary transcript before splicing occurs
5’ Splice Site
at then 5’ end of the intron, usually GU or AU; acts as electrophile attacked by branch point A creating the loop
3’ Splice Site
at 3’ end of intron, usually AG or AC
Branch Point A
A, somewhere in the middle of the intron, surrounding code allows something to bind to it making it so the 2’ hydroxyl sticks out and can act as a nucleophile and attack the 5’ splice site phosphate
U2 snRNP
the part of the spliceosome that binds to the Branch Point A
Alternative Splicing
one transcript can code for many proteins depending on which exons are included in the mRNA and which are spliced out
Annealing mRNA to DNA
If you anneal mRNA to ssDNA, some parts will bind and the rest will form extra loops, in that way you can see introns vs exons
snRNP (small nuclear ribonucleoprotein)
proteins that catalyze splicing, make up the spliceosome
U2 is the one that binds Branch Point A
mutation of snRNP or A would block splicing at that point
Ran
GTP hydrolyzing protein
Ran-GTP and Ran-GDP have different conformations and functions
