1-3 Eukaryotic mRNA are modified at their 5'and 3'ends to facilitate translation. 2025/5/15 21
2025/5/15 21 1-3 Eukaryotic mRNA are modified at their 5’ and 3’ ends to facilitate translation
SNNNNNAUGGNN3 Kozak sequence start stop 5' AUG ☐AAAAA3' 5'cap 0000000000000000000ooa000o0000000000000000 Eukaryotic mRNA uses a methylated cap to recruit the ribosome.Once bound,the ribosome scans the mRNA in a 5'-3'direction to find the AUG start codon. ■ Kozak sequence(Kozak,序列)increases the translation efficiency. Poly-A in the 3'end promotes the efficient recycling of ribosomes. 22
2025/5/15 22 2025/5/15 Once Kozak sequence ◼ Eukaryotic mRNA uses a methylated cap to recruit the ribosome. Once bound, the ribosome scans the mRNA in a 5’-3’ direction to find the AUG start codon. ◼ Kozak sequence（Kozak序列） increases the translation efficiency. ◼ Poly-A in the 3’ end promotes the efficient recycling of ribosomes
poly-A tail SAAAAAAAAAAAAAAA3 G poly-A binding 5'cap start(AUG) protein stop(AGU) Copyright 2004 Pearson Education,Inc.,publishing as Benjamin Cummings
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Kozak sequence: is a sequence which occurs on eukaryotic mRNA and has the consensus ccRccAUGG, where R is a purine (adenine or guanine) three bases upstream of the start codon (AUG),which is followed by another 'G'.The Kozak consensus sequence plays a major role in the initiation of translation process. 2025/5/15 24
2025/5/15 24 Kozak sequence: ◼ is a sequence which occurs on eukaryotic mRNA and has the consensus ccRccAUGG, where R is a purine (adenine or guanine) three bases upstream of the start codon (AUG), which is followed by another 'G'. The Kozak consensus sequence plays a major role in the initiation of translation process
0.2 0.1 0.0 -6-5-4-3-2-1+1+2+3+4 AcCAUGG Kozak sequence 2025/5/15 25
2025/5/15 25 Kozak sequence