Translation: Targeting And Processing

Front 1

proteins assume 3d structure by what?

Back 1

spontaneous folding or chaperone mediated folding

Front 2

How do proteins go to their destination?

Back 2

signal sequence: a hydrophobic sequence at N-terminal of protein

Front 3

Ribosomes synthesize proteins in the ___ or as part of ___

Back 3

cytosol or rER

Front 4

free cytoplasmic ribosomes are destined for where?

Back 4

cytoplasm
nucleus
mitochondria

Front 5

ER-bound ribosomes produce what type of proteins?

Back 5

secreted proteins
plasma membrane proteins
ER proteins
golgi proteins
lysosomal proteins

Front 6

What is the protein traffic approach to transport between ER and the protein destinations?

Back 6

vesicular transport

Front 7

singal hypothesis

Back 7

a stretch of aa (at N-terminus) directs the proteins to specific locations. the signal sequence is subsequently cleaved off

Front 8

In vitro translation of secreted protein

Back 8

experiment comparing translation in cell free system (larger protein) vs with presence of microsomes (smaller protein).

Front 9

microsome

Back 9

ER+ribosomes

Front 10

SRP

Back 10

signal recognition particle:
complex of 300 nucleotides
it recognizes the signal sequence in the cytosol

Front 11

SRP receptor

Back 11

alpha and beta subunit:
an ER membrane protein that binds to SRP

Front 12

translocator

Back 12

an ER membrane protein with a pore

Front 13

signal peptidase

Back 13

cleaves the signal sequence

Front 14

Transmembrane proteins are classified into 5 types. What are they?

Back 14

Type 1-5

Front 15

type 1 transmembrane protein

Back 15

cleavable signal
COO- on cytosol

Front 16

type II transmembrane protein

Back 16

no cleavable signal
NH3+ on cytosol

Front 17

type III transmembrane protein

Back 17

same as type I (no cleavalbe signal)
CYP is an example

Front 18

type IV transmembrane protein

Back 18

multipass
example is GPCR

Front 19

peroxisomes

Back 19

role in transmembrane transport
storage for oxidative enzymes, fatty acid breakdown, and formation of pasmalogen

Front 20

catalase and urate oxidase

Back 20

oxidative enzymes stored in peroxisomes

Front 21

pasmalogen

Back 21

phosholipids found in myelin
formed in peroxisomes

Front 22

Pex

Back 22

23 peroxin membrane proteins participate in importof peroxisomal proteins

Front 23

zellweger syndrome

Back 23

peroxisome transport disorder:
mutation=peroxin Pex2
empty peroxisomes lead to brain, liver, and kidney abnormality...death soon after birth

Front 24

constitutive secretory pathway

Back 24

fusion of the bud to the membrane is unregulated

Front 25

regulated secretory pathway

Back 25

fusion of the bud to the membrane requires a intracellular signaling pathway

Front 26

lysosome functino:

Back 26

store a varitey of hydrolytic enzymes

Front 27

glycosidases, proteases, phosphatases, sulfatases are examples of what kind of enzyme

Back 27

hydrolytic

Front 28

proteins are transported to lysosome by a signal tag_____.

Back 28

mannose-6-P on N-linked oligosaccharide

Front 29

I-cell disease

Back 29

lysosomal storage disease
phase-dense intracytoplamic inclusions in the fibroblasts of pts due to deficiency of GIcNAc-phosphotransferase (mannose-6-P attaching enzyme)

Front 30

I-cell

Back 30

inclusion cell

Front 31

phagocytosis

Back 31

fusion wiht lysosome via phagocytic vacuole

Front 32

pinocytosis

Back 32

uptake of fluid droplets (membrane material)

Front 33

receptor-mediated endocytosis

Back 33

uptake of soluble proteins and high mol vt material
ie. LDL, worn-out plams proteins, mucosal transfer (transcytosis)

Front 34

endocytosis of LDL

Back 34

receptor-mediated
1. LDL binds to LDL receptor and the receptors cluster
2. adaptin and clathrin bind and the coated pit forms
3. coated vescle forms => to lysosomes

Front 35

O-linked protein modification

Back 35

glycosylation at OH groups of serine and threonine residues
1-4 sugar residues

Front 36

N-linked protein modification

Back 36

glycosylation: amide group of asparagine
larger and more complex oligo

Front 37

disulfide bond formation

Back 37

folding
unfolded proteins retained in ER

Front 38

secreted therapeutic proteins expressed in bacteria do not form S-S bonds (not secreted) why?

Back 38

no ER

Front 39

dolichol phasphate

Back 39

85-100 carbon lipid on ER membrane involved in oligosaccharide synthesis and transfer

Front 40

oligosaccharides are assembled on ___ , ___ sugar at a time

Back 40

ER
one

Front 41

alpha1-antitrypsin

Back 41

secreted from hepatocytes and macrophages:
inhibits trypsin and blood protease elastase

Front 42

hereditary emphysema

Back 42

point mutation in alpha1-antitrypsin: mutation causes improper folding and prevents secretion of alpha1-antitrypsin (which accumlates in ER)
=>elastase degrades the fine tissue in lungs

Front 43

damaged cellular proteins, partially unfolded proteins are tagged wtih ___ by ____

Back 43

ubiquitin (76 aa)
ligase complex

Front 44

tagged proteins are degraded by

Back 44

proteasome (proteins and proteases)