真核翻译延伸
中文名称
通路描述
真核翻译延伸周期根据 mRNA 上密码子的顺序，逐个在生长的多肽链上添加一个氨基酸。mRNA 上下一个可用的密码子暴露在三叶草亚基（30S 亚基）的氨酰-tRNA（aa-tRNA）结合位点（A 位点）中。A: 氨酰-tRNA:eEF1A:GTP 的三元复合物进入核糖体，使 tRNA 的反密码子与 mRNA 的 A 位点密码子形成相互作用。B: 当发生特异性识别时，eEF1A:GTP 被带入核糖体的 GTP 酶激活中心，GTP 被水解，eEF1A:GDP 离开核糖体。C: 核糖体的肽基转移酶中心催化新进入的氨基酸与位于肽基-tRNA 结合位点（P 位点）的肽链之间形成肽键。D: 在核糖体的预转位状态下，eEF2:GTP 进入核糖体，物理上将肽基-tRNA 从 A 位点移至 P 位点并离开核糖体，eEF2:GDP 随之离开。eEF2:GTP 的这一动作负责 mRNA 精确移动 3 个核苷酸。因此，去酰基化的 tRNA 被移向 E 位点。一种与核糖体结合的 ATP 酶活性被提议在转位后刺激去酰基化 tRNA 从 E 位点的释放（Elskaya 等人，1991）。在此转位后状态，核糖体现在准备好接受新的三元复合物。该过程用以下图示说明：一个带有氨基酸的氨酰-tRNA，一个带有生长肽链的肽基-tRNA，一个带有-OH 的去酰基化 tRNA，以及一个具有 A、P 和 E 位点的核糖体以容纳这三种形式的 tRNA。
英文描述
Eukaryotic Translation Elongation The translation elongation cycle adds one amino acid at a time to a growing polypeptide according to the sequence of codons found in the mRNA. The next available codon on the mRNA is exposed in the aminoacyl-tRNA (aa-tRNA) binding site (A site) on the 30S subunit.
A: Ternary complexes of aa -tRNA:eEF1A:GTP enter the ribosome and enable the anticodon of the tRNA to make a codon/anticodon interaction with the A-site codon of the mRNA. B: Upon cognate recognition, the eEF1A:GTP is brought into the GTPase activating center of the ribosome, GTP is hydrolyzed and eEF1A:GDP leaves the ribosome. C: The peptidyl transferase center of ribosome catalyses the formation of a peptide bond between the incoming amino acid and the peptide found in the peptidyl-tRNA binding site (P site). D: In the pre-translocation state of the ribosome, the eEF2:GTP enters the ribosome, physically translocating the peptidyl-tRNA out of the A site to P site and leaves the ribosome eEF2:GDP. This action of eEF2:GTP accounts for the precise movement of the mRNA by 3 nucleotides.Consequently, deacylated tRNA is shifted to the E site. A ribosome associated ATPase activity is proposed to stimulate the release of deacylated tRNA from the E site subsequent to translocation (Elskaya et al., 1991). In this post-translocation state, the ribosome is now ready to receive a new ternary complex.
This process is illustrated below with: an amino acyl-tRNA with an amino acid, a peptidyl-tRNA with a growing peptide, a deacylated tRNA with an -OH, and a ribosome with A,P and E sites to accommodate these three forms of tRNA.
A: Ternary complexes of aa -tRNA:eEF1A:GTP enter the ribosome and enable the anticodon of the tRNA to make a codon/anticodon interaction with the A-site codon of the mRNA. B: Upon cognate recognition, the eEF1A:GTP is brought into the GTPase activating center of the ribosome, GTP is hydrolyzed and eEF1A:GDP leaves the ribosome. C: The peptidyl transferase center of ribosome catalyses the formation of a peptide bond between the incoming amino acid and the peptide found in the peptidyl-tRNA binding site (P site). D: In the pre-translocation state of the ribosome, the eEF2:GTP enters the ribosome, physically translocating the peptidyl-tRNA out of the A site to P site and leaves the ribosome eEF2:GDP. This action of eEF2:GTP accounts for the precise movement of the mRNA by 3 nucleotides.Consequently, deacylated tRNA is shifted to the E site. A ribosome associated ATPase activity is proposed to stimulate the release of deacylated tRNA from the E site subsequent to translocation (Elskaya et al., 1991). In this post-translocation state, the ribosome is now ready to receive a new ternary complex.
This process is illustrated below with: an amino acyl-tRNA with an amino acid, a peptidyl-tRNA with a growing peptide, a deacylated tRNA with an -OH, and a ribosome with A,P and E sites to accommodate these three forms of tRNA.
所含基因
6 个基因