Translation
Translation
Composition of ribosomes 2 subunits, each composed of about 60% RNA and about 40% protein(by mass) Small ribosomal subunit 1 rRNA(bacteria), 18S rRNA(eukaryotes) 21(bacteria) to 33(eukaryote) proteins Initial binding of mRNA and initiator met-tRNA Large ribosomal subunit 23s 5s rRNA(bacteria), 28S, 5.8S,& 5srrNA (eukaryotes 31(bacteria) to 49(eukaryote) proteins Forms complete, catalytic ribosome
Composition of ribosomes • 2 subunits, each composed of about 60% RNA and about 40% protein (by mass). • Small ribosomal subunit – 16S rRNA (bacteria), 18S rRNA (eukaryotes) – 21 (bacteria) to 33 (eukaryote) proteins – Initial binding of mRNA and initiator met-tRNA • Large ribosomal subunit – 23S & 5S rRNA (bacteria), 28S, 5.8S, & 5S rRNA (eukaryotes) – 31 (bacteria) to 49 (eukaryote) proteins – Forms complete, catalytic ribosome
Ribosomes核糖体 原核和真核生物核糖体的组成及功能 核糖体亚基 TRNAs蛋白 RNA的特异顺序和功能 细菌 70S50s23s-2904b31种(L1-31)含 CGAAC和 GTyCG互补 2.5×106D 5S=120b 66RNA 30S 16$=1542b 21F+(S1-S21)16SRNA(CCUCCU)FHS-D 顺序( AGGAGG)互补 哺乳动物 80S60S28S-4718b49种有GAUC和RNAM的TvCG互补 4.2×106D 5S=120b 60%RNA 5.8S=160b 40S18S=1874b33种 和Capm7G结合
Ribosomes核糖体 原核和真核生物核糖体的组成及功能 核糖体亚基 rRNAs 蛋白 RNA的特异顺序和功能 细菌 70S 50S 23S=2904b 31种(L1-L31）含CGAAC和GTψCG互补 2.5×106D 5S=120b 66%RNA 30S 16S=1542b 21种(S1-S21) 16SRNA(CCUCCU)和S-D 顺序(AGGAGG)互补 哺乳动物 80S 60S 28S=4718b 49种 有GAUC和tRNAfMat的TψCG互补 4.2×106D 5S=120b 60%RNA 5.8S=160b 40S 18S=1874b 33种 和Capm7G结合
核糖体的作用位点 (1)A位点(或称 acceptor site)可以进入 氨基酰RNA( aminoacyl-RNA) (2)P位点(或称供位, donor site)是被肽基 酰+RNA( peptidyl-tRNA)所占据。 (3位点 Exit site)脱性tRNA( deacylated tRNA)短暂地占据
核糖体的作用位点 • ⑴A位点（或称 acceptor site）可以进入 氨基酰-tRNA(aminoacyl-tRNA)。 • ⑵ P位点(或称供位，donor site) 是被肽基 酰-tRNA(peptidyl-tRNA)所占据。 • (3)E位点(Exit site) 脱酰tRNA(deacylatedtRNA)短暂地占据
3 sites on ribosome for interaction with tRNAs E A CH3 CH2 NH+CH-C÷NH亠cH-CAcc5 NH,CH-C=ACC Exit site for alanylcysteiny l-tRNA ethionyl-tRNA m free tRNA ACA 5 AC 5 peptidyl-tRNA aminoacyl-tRNA
3 sites on ribosome for interaction with tRNAs E P A 5' UAC 5' 2 methionyl-tRNA met 2 3 ACC O C 2 CH CH NH CH S CH m 5' SH 2 2 ACA 5' ACC O CH C CH NH 3 O CH C CH NH alanylcysteinyl-tRNA cys peptidyl-tRNA aminoacyl-tRNA Exit site for free tRNA