INTRACELLULAR TRAFICKING

Question 1

ENDOCYTOSIS

Answer 1

– Clathrin-mediated endocytosis (receptor-dependent)adaptin
– Potocytosis (receptor-dependent in caveolae)
– Macropinocytosis
– Phagocytosis

Question 2

• exocytosis

Answer 2

– constitutive

– regulated (Ca2+ triggered)

Question 3

Formation of vesicle

Answer 3

Initiation, invagination, constriction, fission, uncoating

Question 4

From ER–> golgi

Answer 4

COP II by help of Sar1 (GTP binding protein)

Question 5

From golgi–>er/ PM

Answer 5

COP I by help of ARF (GTP binding protein)

Question 6

Rab

Answer 6

control most steps of vesicle transport

Question 7

Recognition of the target membrane through

Answer 7

SNARE
v-snare and t-snare
v=vesicle t=target membrane

Question 8

Actin

Answer 8

• Globular proteins (α,β,γ types)
• polarized polymerization (pointed and barbed ends)
• function: (moving organelles, cellular motion
cell adhesion structures, maintenance of cell volume

Question 9

Intermediate filaments

Answer 9

No polarity
No motor proteins associated
High tensile strength
Resistant to compression,
twisting and bending forces
Heterogeneous

Question 10

Microtubules

Answer 10

• polymers of tubulin subunits
• alpha and beta-tubulins
• polarized polymerization (- and + ends)
• tube formed by 13 polymers (23 nm diameter)
• negative end at the microtubule organizing center
(MTOC): centriole or basal body
• function: organelle movements, mitotic spindle,
cilia and flagella

Question 11

Colchicine

Answer 11

“mitotic poison” or spindle poison
binds to tubulin and inhibits
microtubule polymerization

Question 12

Motor proteins associated to microtubules:

Answer 12

dyneins and kinesins

Question 13

Translocation complex in mitochondria

Answer 13

TOM and TIM

Question 14

NLS

Answer 14

Nucleas localization signal that interact with importins and ran

Question 15

Ran GAP

Answer 15

RAN + GTP–>RAN GDP with help of Ran GAP

Question 16

RAN GEP

Answer 16

Ran GDP–> ran takes away Gdp from RAN in nucleus

Question 17

SRP

Answer 17

signal recognition particle at N-terminus of poly Pwhich interact with SRP-receptor and GTP gets hydrolyzed

Question 18

translocon

Answer 18

3 membrane protein, forming a protein conducting channel in ER

Question 19

signal peptidase

Answer 19

cleavage of SNP of protein

Question 20

how does protein bind to translocon

Answer 20

by hydrophobic interactions

Question 21

PTS

Answer 21

PTS 1 on carboxyl termianal

PTS2 on amino terminal

Question 22

PEX 5

Answer 22

PTS 1 forms complex with pex 5

Question 23

PEX 7

Answer 23

PTS 2 forms complex with pex 7

Question 24

ATP in peroxisom

Answer 24

Matrix proteins need ATP and membrane proteins doesnt

Question 25

Chaperone

Answer 25

assist in covalent folding or unfolding of proteins

Question 26

Hsp 70

Answer 26

Acts as chaperone in mitochondria preventing folding of protein

Question 27

BIP

Answer 27

Binding immunoglobin protein | prevents aggregation and prompts proper folding

Question 28

Example of post translational translocation

Answer 28

Cytochrome B5

Question 29

KDEL

Answer 29

ER retention signal | golgi--> er cop I

Question 30

ERAD

Answer 30

ER associated degradation | takes care of proteins that have been missfolded to enter proteasomes

Question 31

P97

Answer 31

ATP source for ERAD

Question 32

Two pathways for degradation

Answer 32

Lysosomal proteases, NO ATP | Ubiquitin, ATP

Question 33

Enzymes of protein degradation

Answer 33

E1-activation enzyme E2- conjugation enzyme E3- ligase enzym

Question 34

Minimuma amount of ubiquitin molecules to be present to degrade protein

Answer 34

4

Question 35

The endomembrane system

Answer 35

* nuclear envelope * endoplasmic reticulum (ER) * Golgi apparatus * lysosome (phagosome, autophagosome) * endosome * transport vesicles * cell membrane * peroxisome (?) Mitochondria • inner and outer mitochondrial membranes

Question 36

N-linked glycosylation

Answer 36

The attachment of oligosaccharide, glycan to a nitrogen atom (amide nitrogen of asparagine (Asn) residue of a protein in ER

Question 37

Function of golgi

Answer 37

``` glycoprotein maturation O-glycosylation limited proteolysis protein sorting synthesis of sphingomyelin, glycolipids, proteoglycans, polysaccharides, glucosaminoglycans ```

Question 38

Lysosome

Answer 38

Its enzymes can break up almost anything.

Question 39

Enzymes in lysosome

Answer 39

``` – DNAse, RNAse – proteases (e.g. cathepsins) – glycosidases – lipases – phosphatases – sulfatases ```

Question 40

Mitochondria matrix

Answer 40

``` Matrix nucleoid, ribosomes, large enzyme complexes ```

Question 41

Mitochondria Inner membrane

Answer 41

impermeable protein: lipid ratio > 3:1 - transporters for metabolites and proteins - enzymes of oxidative phosphorylation - proteins of fusion and fission

Question 42

Mitochondria outer membrane

Answer 42

pores (porin) | permeable for up to 5 KDa

Question 43

N-glycosylation

Answer 43

dolichol | arginine, glucose, mannose, N-acetylglucose-amine