P69 (a) Cell-free protein synthesis; no microsomes present Add microsome membranes 3⊥ -terminal signal sequence Completed proteins No removal of with signal se signal sequence no transport of protein into (b)Cell-free protein synthesis; microsomes present 80 Cotranslational Removal of signal transport of protein sequence into microsome
P697
There are at least two types of sorting signals on proteins One type resides in a continuous stretch of amino acid sequence(a single stretch, or bipartite), called as signal peptides or presequences (targeting sequences, leading peptides) used to direct moving to ER, Nucleus, Mit, ChI etc typically 15 to 60 residues long for ER. These signal peptides are usually removed from finished protein by a specialized signal peptidase once the sorting process has been completed Some other: signal peptides (internal topogenic sequence) retain in the acrossed membrane to be the membranous parts of integrated protein in certain organelles. The other type consists of a specific three-dimensional arrangement of atoms on the folded, even sugar residue-marked proteins surface, called as signal patch to bind to a matched three-dimensional domain or motif of a receptor in the appropriate membrane of certain organelles. Such as M6-P marked lysosomal enzymes move from gC to lysosomes
There are at least two types of sorting signals on proteins. One type resides in a continuous stretch of amino acid sequence (a single stretch, or bipartite), called as signal peptides or presequences (targeting sequences, leading peptides) used to direct moving to ER, Nucleus, Mit, Chl etc., typically 15 to 60 residues long for ER. These signal peptides are usually removed from finished protein by a specialized signal peptidase once the sorting process has been completed. Some other signal peptides (internal topogenic sequence) retain in the acrossed membrane to be the membranous parts of integrated protein in certain organelles. The other type consists of a specific three-dimensional arrangement of atoms on the folded, even sugar residue-marked protein’s surface, called as signal patch to bind to a matched three-dimensional domain or motif of a receptor in the appropriate membrane of certain organelles. Such as M6-P marked lysosomal enzymes move from GC to lysosomes
Some typical signal peptides Function of Signal peptide Sign Import inteR e.g.TH3N-Met-Met-Ser-Phe-Val-Ser-Leu-Ler-Leu-Val-Gly-Ile-Ler Phe-Trp-Ala-Thr-Glu-Ala-Glu-GIn-Leu-Thr-Lys-Cys-Glu-Val-Phe (5-10 residues Retain in Lys-Asp-Glu-Leu-COO(KDEL) lumen of er Import into Mit H3N-Met-Leu-Ser-Leu-Arg-Gln-Ser-lle-Arg-Phe-Phe-Lys-Pr o-Ala-Thr-Arg-Thr-Leu-Cys-Ser-Ser-Arg-Tyr-Leu-Leu- Import into and e.g. for SV40T antigen, -Pro-Pro-Lys-Lys-Arg-Lys-Val-(NLS export out of nucleus nuclear-localiz ignal, rich in Lys and Arg basic aa)versus NES (leu- rich nuclear -export signal Import into e.g.-Ser-Lys-Leu- peroxisome Attach to membranes H,N- Gly-Ser-Ser-Lys-Ser-Lys-Pro-Lys- of myristic acid to the N-end
Some typical signal peptides 信号功能 Attach to membranes via the covalent linkage of myristic acid to the N-end + H3N- Gly-Ser-Ser-Lys-Ser-Lys-Pro-Lys- Function of signal peptide Signal peptide Import intoER e.g. +H3N-Met-Met-Ser-Phe-Val-Ser-Leu-Ler-Leu-Val-Gly-Ile-LeuPhe-Trp-Ala-Thr-Glu-Ala-Glu-Gln-Leu-Thr-Lys-Cys-Glu-Val-Phe -Gln (5-10 hydrophobic residues among 15-06 residues)Hrere3N-Met-Met-Ser-Phe-Val-Ser-Leu-Ler-Leu-Val-GlyIle-Leu-Phe-Trp-Ala-Thr-Glu-Ala-Glu-Gln-Leu-ThrLys-Cys-Glu-Val-Phe-GlnRetain in lumen of ER -Lys-Asp-Glu-Leu-COO- (KDEL) Import into Mit. e.g. +H3N-Met-Leu-Ser-Leu-Arg-Gln-Ser-Ile-Arg-Phe-Phe-Lys-Pr o-Ala-Thr-Arg-Thr-Leu-Cys-Ser-Ser-Arg-Tyr-Leu-Leu- ( N-end-[positive charged residue-hydrophobic residues]n-) Import into and export out of nucleus e.g. for SV40T antigen,-Pro-Pro-Lys-Lys-Arg-Lys-Val- (NLS, nuclear-localization signal, rich in Lys and Arg basic aa) versus NES (leu-.rich nuclear-export signal) Import into peroxisome e.g.-Ser-Lys-Leu-
号酶作用位点 N n MK-- WVTFISSLLFLF-SSAYS 血清白蛋白 MKVKEKYQHL--WRWGWRWGTM LLGMLMT—CsA HIV- 1gp160 信号肽的一级序列 信号肽一级序列由疏水核心(h)、C端(c)和N端(n)三个区域构成。 以血清白蛋白和HⅣ-1型病毒的糖蛋白gp160信号肽为例,显示出两者的n区长度明显不同
信号肽的一级序列 信号肽一级序列由疏水核心（h）、C端（c）和N端（n）三个区域构成。 以血清白蛋白和HIV-1型病毒的糖蛋白gp160信号肽为例，显示出两者的n区长度明显不同
UDP Lysosomal enzyme GIcNAc 令 osphodiesterase UMP Signal sequences GlcNAc phosphotransferase Catalytic site Recognition site
P720