一、Term
Aminoacyl tRNA synthetases氨酰tRNA合成酶
Shine-Dalgarno sequence SD序列
Wobble hypothesis (摆动假说)
二、
在细胞质中会发生subunit exchange
三、Preinitiation起始前准备
（一）tRNA charging
amino acid (aa) + ATP + tRNA --> aminoacyl-tRNA + AMP + 2 Pi
（二）Dissociation of Ribosomes核糖体的解离
Ribosomes dissociate into subunits at the end of each round of translation
RF and EF-G actively promotes this dissociation
IF3 binds to free 30S subunit and prevents reassociation with 50S subunit to form a whole ribosome
四、Initiation
Once the ribosomomal subunits have been dissociated, the cell builds a complex on the 30S subunit:
- mRNA
- Aminoacyl-tRNA
- Initiation factors
- IF3 binds by itself to 30S subunit
- IF1 and IF2 stabilize this binding
- IF2 can bind alone, but is stabilized with help of IF1 and IF3
- IF1 does not bind alone
Prokaryotic initiation codon is:
通常是AUG
可以是 GUG但是很少是UUG
Initiating aminoacyl-tRNA ：N-formyl- methionyl-tRNA（N-甲酰甲硫氨tRNA）
N-formyl-methionine (fMet) is the first amino acid incorporated into a polypeptide
起始氨基酸：fMet，N-甲酰甲硫氨酸
This amino acid is frequently removed from the protein during maturation
蛋白成熟后会被移除
30s起始复合体：30S亚基、mRNA、fMet-tRNA、GTP、IF1、IF2、IF3
IF3介导mRNA的SD序列和16s rRNA的3‘端互补配对，这个过程也由IF1、IF2协助，此时这三个起始因子都已经结合到30s上
IF2是促进fMet-tRNA与30S起始复合物结合的主要因素，这个过程也要IF1、3，还要GTP，这时GTP还不被水解，而是等到50S结合后被水解
1. In what direction does the ribosome read the mRNA? In what direction is a polypeptide synthesized?从5’到 3’; 氨基amino到羧基 carboxyl
2. What is the nature of the genetic code that dictates which aa will be incorporated in response to the mRNA?
五、Elongation
- EF-Tu: EF-Tu –GTP escort aminoacyl-tRNAs to the ribosome护送氨酰tRNA进入核糖体
- EF-Ts: regenerates EF-Tu-GTP 再生EF-Tu-GTP
- EF-G: help translocation帮助易位
六、Termination
Release factors (RFs) enter the A site
七、Post-translational Modifications
Cleavage：去除信号肽、修建N端C端
Chemical modifications化学修饰
acetylation (乙酰基化), hydroxylation (羟化 ), phosphorylation (磷酸化), methylation, glycosylation (糖基化)
Disulfide bond二硫键
