tRNA charging reaction 20 synthetases Figure 17.2 H O Aminoacyl-tRNA H,N-C-co0+⊙⊙⊙ synthetase HN-C-C-0- pp ⑧ OH OH OHOH () Amino acid ATP Aminoacyl-AMP H HN-0-® Aminoacyl-tRNA synthetase ⑧ OHOH OH OH OH OH Aminoacyl-AMP tRNA C=0 (2) (Terminal AMP adenosine) HN-C-一H ⑧ Aminoacyl-tRNA
tRNA charging reaction 20 synthetases
小结 √氨基酰-RNA合成酶连接氨基酸到它们 同源的tRNAs。 √这一过程通过两步特定的反应由ATP活 化氨基酸生成AA-RNA和AMP
小 结 ✓氨基酰-tRNA合成酶连接氨基酸到它们 同源的tRNAs。 ✓这一过程通过两步特定的反应由ATP活 化氨基酸生成AA-tRNA和AMP
Dissociation of ribosome .ribosome:contain 30s and 70s subunit .Two subunit have to dissociate after each round of translation for a new initiation complex. .The initiation factors that involve ribosome dissociation. ·IF-1 .IF-1 is actively promoting the dissociation. ·IF-3 .IF-3 binds to the free 30s subunits and prevents their reassociation with 50s subunits
Dissociation of ribosome •ribosome: contain 30S and 70S subunit •Two subunit have to dissociate after each round of translation for a new initiation complex. •The initiation factors that involve ribosome dissociation. •IF-1 •IF-1 is actively promoting the dissociation. •IF-3 •IF-3 binds to the free 30S subunits and prevents their reassociation with 50S subunits
Demonstration of ribosomal subunit exchange No exchange: Growth in light medium Heavy ribosome Heavy ribosome Light ribosome (labeled) (labeled) (unlabeled) Subunit exchange: Growth in light *50S medium *30S 火 Figure 17.3 Hybrid ribosomes Exchange (labeled) partners
Demonstration of ribosomal subunit exchange
10 Heavy:86S Light 0 hybrid ribosomal subunit can exchange 86S 70S (Heavy)Light) 01020304050607080 Figure 174
hybrid ➔ ribosomal subunit can exchange