LIFESCI 3 Lecture Notes - Lecture 14: Endoplasmic Reticulum, Kozak Consensus Sequence, Differential Centrifugation
Document Summary
Methionine is modified at n terminus w/ formyl group. 5 - 10 nucs in front of aug start codon. Measurement of mass based on density gradient centrifugation. Many shine dalgarno seq on mrna allows for this. Allows polypeptides to be synthesized simultaneously and independently. If1 and if2 (gtp binding protein/gtpase) bind to 30s i. If3 helps 16s rrna bind to mrna after it recognizes sd sequence. If2 helps initiator methionyl-trna^fmet bind to start codon at p site b/c a site is blocked. 30s initiation complex is formed (if1,2,3, small subunit, initiator. 30s initiation complex is formed (if1,2,3, small subunit, initiator trna) 50s binds to 30s -> 70s initiation complex formed trna at p site of 70s. Peptide bond forms between aas from a and p sites. No trna corresponding to stop codon, but instead has corresponding rf. Nucleolus very apparent during g1/g2 phase - this is when ribosomes are produced the most.
