Chapter

9Endomembrane

System,

ProteinSorting

And

Membrane

Traffic內(nèi)膜系統(tǒng)、蛋白質(zhì)分選、膜Lecture

1（

:By：）OUTLINEIntroductionEndoplasmic

ReticulumGolgi

complexLysosomesSecretory

and

EndocytosisThe

Mechanism

of

Vesicula

TransportMembrane-bound

organelle(膜結(jié)合細(xì)胞器)：organelles

or

compartments

that

possess

the

membranestructureCytoplasmic

membrane

system(細(xì)胞質(zhì)膜系統(tǒng))：organelles

are

correlate

with

cytoplasmic

membrane

about

biogenesis(在生物發(fā)生上與質(zhì)膜相關(guān)的細(xì)胞器)Endomembrane

system(內(nèi)膜系統(tǒng))：membranous

organelles

within

the

cytoplasm

which

are

interrelated

instructures,functionsandoccurrence.(結(jié)構(gòu)、功能、發(fā)生密切相關(guān)的內(nèi)膜結(jié)構(gòu))：nuclear

membrane,

endoplasmic

reticulum,

Golgi

complex,

lysosomes,endosomes,

vacuoles,

vesicles.9.1.1

Membrane-bound

Organelleand

Endomembrane

system The

characteristicsof

endomembrane

systemDynamic,

interconnected

networkpathways

:biosynthetic

pathwaysecretory

pathway(

途徑)endocytic

pathway(內(nèi)吞途徑) Biological

Meanings

OfEndomembrane

System區(qū)室化動(dòng)態(tài)9.1.2 Protein

Sorting

蛋白質(zhì)分選Protein ing

or

proteinsortingWHEN

and

HOWProtein

translocation----回答

“when”co-translational

translocation(共翻譯轉(zhuǎn)運(yùn))

一邊

一邊轉(zhuǎn)運(yùn)post-translational

translocation(翻譯后轉(zhuǎn)運(yùn))

先

再轉(zhuǎn)運(yùn)(1)

co-translational

translocationMembrane-bound

ribosome(2)

post-translational

translocationFree

ribosome(1)Through

nuclear

poreAcross

membraneBy

vesicleMechanisms

OfProteining蛋白質(zhì)分選的三種機(jī)制-----回答“how”nuclear

porevesicleacrossmembraneSorting

Signal

directs

the

newly

madeprotein

to

a

proper

destination與生俱來(lái)的三種信號(hào)序列信號(hào)加工信號(hào)定位信號(hào)▲核定位信號(hào)▲引導(dǎo)肽▲信號(hào)肽1.

Transport

through

nuclear

poreProteins

bound

for

the

Nucleus

；

synthesized

by

free

ribosomes

in

cytosolNuclear

localization

signal

(核定位信號(hào),NLS) VS.

nuclearimport

receptor

protein(核輸入蛋白)nuclearlocalizationsignal,

NLSnuclear

import

receptorprotein2.

Transport

across

membraneProteins

bound

for oplasmic

reticulum,mitochondrion,

chloroplast

and

peroxisome;synthesized

by

free

ribosomes

in

cytosolLeading

peptide

（引導(dǎo)肽）

VS.protein

translocators

（蛋白轉(zhuǎn)運(yùn)蛋白）3.

Transport

by

vesicleProteins

moving

from

one

compartment

to

another

oroutside

of

cellsynthesized

by

membrane-bound

ribosomes

in

cytosolSecretory

protein:

Signal

peptide

信號(hào)肽

RER

COPⅡ

coated

vesicle

Golgi

complexclathrin

coated

vesicle

outside

of

cell9.2

Endoplasmic

reticulum

(ER)18971945,Garnier found“kinoplasm

動(dòng)質(zhì)”Port confirmed

ER

under

EM??1940

~60

era,

focus

on

structure

researchAfter

70

era,

focus

on

function

research9.2.1

Morphology

and

ChemicalComposition

morphologyShape:tubules管狀,vesicles

泡狀and

sacs

扁平network

of囊狀that

areinterconnected

;thickness

is

5-6

nm;Two

surface

兩個(gè)面：luminal

surface

or

cisternal

surface(潴泡面）cytoplasmic

surface

（胞質(zhì)溶膠面）ER is

the

largest

organelle

in

most

eukaryoticcells.Its

membrane

may

account

for

about

half

of

allcell

membrane

system.the

space

enclosed

by

the

ER

may

representabout

10%

of

the

total

cell

volume.

chemical

composition

andenzymesMade

up

of

protein

and

lipidphospholipid(磷脂)protein30%~40%60%~70%Marker

Enzyme(標(biāo)志酶):glucose

6-phosphatase(葡萄糖-6-磷酸酶)9.2.1內(nèi)質(zhì)網(wǎng)的類型Rough

endoplasmic

reticulum

(RER)扁平潴泡為多，

蛋白、多種膜蛋白、酶蛋白Smooth

endoplasmic

reticulum

(SER)常為小的管狀和小的泡狀結(jié)構(gòu)。廣泛存在與多種細(xì)胞中。特殊類型的內(nèi)質(zhì)網(wǎng)微粒體(microsome)肌質(zhì)網(wǎng)(sarcoplasmic

reticulum)9.2.2

Main

Functions

of

SERglycogenolysis

andrelease

of

glucose(糖原分解與釋放)Synthesis

of

lipids

and

transport(脂

與轉(zhuǎn)運(yùn)))Synthesis

of

steroid

hormones(類固醇激素Detoxification

in

the

liver

cell(肝細(xì)胞解毒)Regulate

Ca2+concentration(調(diào)節(jié)鈣離子濃度)1.

glycogenolysis

and

release

of

glucose2.

Synthesis

of

lipids

and

transportSynthesis（

）SER

cytoplasmic

surfaceflip（翻轉(zhuǎn)）翻轉(zhuǎn)酶的作用transport（轉(zhuǎn)運(yùn)）vesicles

and

phospholipid

transfer

protein脂酰輔酶A磷酸甘油磷脂酸甘油二脂卵磷脂磷脂的mitochondrion,chloroplast

andperoxisome①transport

vesicle(小泡)Golgi

complex(高復(fù)合體)Lysosome(溶酶體)Cell

membrane②phospholipid

transfer

protein(PLTP，磷脂轉(zhuǎn)運(yùn)蛋白)磷脂的轉(zhuǎn)運(yùn)磷脂交換蛋白的作用3.

Synthesis

of

steroid

hormone類固醇激素(STH)Adrenal

cell(腎上腺細(xì)胞)、interstitial

cell(睪丸間質(zhì)細(xì)胞,

又稱

細(xì)胞Leydig

cell)、luteal

cells(

細(xì)胞)Synthesis

of

STH:acetyl

CoA

Cholesterol

steroid

hormone30步4.

Detoxification

in

the

liver

cellSER

contains

abundant

oxygenases(氧化酶),such

as

cytochrome

P450s（細(xì)胞色素P450）、NADH-cytochrome

C

redu e

(NADH-細(xì)胞色素還原酶),etc,混合功能的氧化酶(mixed-function

oxidase)–

每分子的底物被氧化需要消耗一分子氧,并且將NADPH轉(zhuǎn)變成NADP+,該氧化過(guò)程消耗的氧分子中有一個(gè)氧原子出現(xiàn)在水中，另一個(gè)氧原子出現(xiàn)在產(chǎn)物中,故此將催化該反應(yīng)的酶稱為混合功能的氧化酶。5.

Modulate

Ca2+

concentrationSarcoplasmic

reticulum

肌質(zhì)網(wǎng):SER

instriated(橫紋)muscle

cells,sequestering

(隔絕)calcium

ions

within

the

cisternal

spaceCa2+releaseCa2+

recoverMusclecontractionMusclerelaxingCa2+肌質(zhì)網(wǎng)有關(guān)粗面內(nèi)質(zhì)網(wǎng)的發(fā)達(dá)程度可作為細(xì)胞分化程度和功能狀態(tài)的一種形態(tài)特征，下面哪種說(shuō)法是錯(cuò)誤的：A．分化程度低的細(xì)胞，粗面內(nèi)質(zhì)網(wǎng)不發(fā)達(dá)B．胰腺細(xì)胞中粗面內(nèi)質(zhì)網(wǎng)發(fā)達(dá)C．胚胎細(xì)胞及干細(xì)胞中粗面內(nèi)質(zhì)網(wǎng)不發(fā)達(dá)D．漿細(xì)胞中粗面內(nèi)質(zhì)網(wǎng)發(fā)達(dá)E．生長(zhǎng)速度快，惡性程度高的腫瘤細(xì)胞中，粗面內(nèi)質(zhì)網(wǎng)發(fā)達(dá)9.2.3粗面內(nèi)質(zhì)網(wǎng)的功能--信號(hào)肽與蛋白質(zhì)膜結(jié)合核糖體

蛋白質(zhì)的去向（P355）蛋白到ER

腔中的蛋白質(zhì)RER中的酶類基體的酶溶酶體的酶整合膜蛋白ER膜的糖蛋白基體的膜糖蛋白溶酶體的膜糖蛋白質(zhì)膜糖蛋白核膜糖蛋白質(zhì)膜脂錨定蛋白（位于質(zhì)膜的外側(cè)面）質(zhì)膜的外周蛋白（位于質(zhì)膜的外側(cè)面）32蛋白質(zhì)進(jìn)入核糖體實(shí)驗(yàn)信號(hào)肽的證實(shí)G.Blobel等用離體實(shí)驗(yàn)證實(shí)了信號(hào)肽的存在:RER對(duì)產(chǎn)物的影響蛋白水解酶實(shí)驗(yàn)多聚核糖體的離體翻譯體外實(shí)驗(yàn)多聚核糖體實(shí)驗(yàn)信號(hào)序列的特性序列特征15-35個(gè)氨基酸殘基，N端含有1個(gè)或多個(gè)帶正電荷的氨基酸，其后含有6-12個(gè)疏水殘基位置:N-端突出的一段肽內(nèi)含信號(hào)肽早期信號(hào)假說(shuō)(signal

hypothesis)1975年，Blobel等正式提出了信號(hào)假說(shuō),要點(diǎn)是:蛋白

始于游離核糖體;N端信號(hào)序列靠

碰撞與內(nèi)質(zhì)網(wǎng)膜接觸,然后

內(nèi)質(zhì)網(wǎng)的膜;蛋白質(zhì)以袢環(huán)形式穿過(guò)內(nèi)質(zhì)網(wǎng)的膜;蛋白的存在方式:若信號(hào)序列被信號(hào)肽酶切除:完全進(jìn)入腔若是停止轉(zhuǎn)移信號(hào):膜蛋白信號(hào)識(shí)別顆粒與停靠蛋白－信號(hào)假說(shuō)的補(bǔ)充signal

recognition

partical, SRP

信號(hào)識(shí)別蛋白SRP

is

a

cytosolic

ribonucleoprotein

particle

核糖