Translation initiation

jambomber's version from 2015-05-10 12:04

Section 1

Question Answer
How many polypeptides are involve in euk initation vs prok?3 IFs vs 28 polypeptides >1.6MDa comple lager than 40S sub unit. Indicative of increased comlexity
What similarities exist b/w p + euks?Met TRNA initator + Elongation
Where was translation discovered?Mammals and subsequently eubacteria
How was the role of the 5' CAP est?In rabbit retic nuclease 5' 7mGpp more efficiently translated than Gppp
How was AUG recognised as init codon?Inhibit elongation w/ sparsomycin - AUG invariably protected
Which viruses encode a protease that prevents translationPicornoviruses
How many polypeptides in EIF312- it is exceeding complex and orchestrates rest of initiaion factor
How are euk and prok IFs related1A=IF1 5b=IF2 1=IF3
How do the IRES['s of distictovirsuses work?-180nt sequnce forms two overlapping pseudoknots which occupt E and P sites. Initiator codon specfiied by folowing mimics. eEF1 delivers charged tRNA
How does the HEPC IRES work?-450nt - med complexity. Binds salt washed 40S in absence of IFs and does not require 4F or GTP hydolrsis
What insight is obtained from HEPC?That eiF4 only functions to load primed ribosomes onto RNA
What are the most complex IRES's?1600ts in picornoviruses ie Polio Type I and EMCV type II
How do Picornovirus IRES's work?25 Nt downstream conserved Aug x where init occurs. Next AUG downstream. Scanning? Shunting? All except eiF4E+ work with Cleaved 4G

Section 2

Question Answer
How are scanning models an oversimlificationDont facto in 3,5,2,1 TC form a MFC in vivo
How lonh might IFs be retained after elongation begins?20 seconds?

Section 3

Question Answer
What prupose do 3, 1 and 1A serve?Prevent association b/w ribosomal sub unit
What is 40S orgnaised intoHead, Neck( RNA channel) and Body