09a: Protein Trafficking Flashcards Preview

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Flashcards in 09a: Protein Trafficking Deck (36):
1

T/F: synthesis of all proteins begins on cytoplasmic ribosomes.

True

2

Proteins translated on cytoplasmic ribosomes are targeted to:

1. Cytoplasm
2. Mitochondria
3. Nucleus

3

Proteins translated on RER ribosomes are targeted to:

1. Cell membrane
2. Lysosomes
3. Cell secretion

4

What's the power house of protein synthesis?

RER

5

Information that determines site of a protein's localization is found in its (primary/secondary/tertiary) structure.

Primary

6

Cytoplasmic protein have which signal?

No signal

7

Mitochondrial protein have which signal?

Pre-sequence with amiphipathic character (hydrophobic and positively-charged AA) on N-terminus

8

Nuclear proteins have which signal?

Lys-Lys-Lys-Arg-Lys

9

Membrane proteins have which signal?

Core of hydrophobic AA near N terminus

10

Secretory proteins have which signal?

Core of hydrophobic AA near N terminus

11

Lysosomal proteins have which signal?

Mannose-6-P

12

SRP stands for (X) and is similar in composition to (Y).

X = Signal Recognition Particle
Y = snRNPs (has RNA and protein components)

13

What's the function of SRPs?

Bind signal peptide on secretory, membrane, lysosomal proteins that have begun translation on cytoplasmic ribosomes

14

Once SRP binds (X), translation is paused until:

X = signal peptide

SRP binds its receptor on ER membrane

15

T/F: Ribosomes on ER are fixed on the membrane.

False - when SRP binds signal peptide, it carries ribosome to ER to continue translation of the protein

16

T/F: Signal peptide is removed from mature polypeptide chain once translation and translocation is complete.

True - cleaved by signal peptidase

17

Simple, one-pass transmembrane proteins have (X) sequence that's composed of (Y) AA.

X = stop-transfer
Y = core of hydrophobic

18

Glycosylation of Asn residues occurs in (ER/Golgi/cytoplasm).

ER

19

Glycosylation of Ser residues occurs in (ER/Golgi/cytoplasm).

Golgi

20

Glycosylation of Thr residues occurs in (ER/Golgi/cytoplasm).

Golgi

21

The initial glycans added to (X) in ER have which key component?

X = Asn (X-Ser/Thr)

Mannose

22

In ER, which regions/bonds are too difficult to assemble with chaperones alone?

1. Pro regions
2. Disulfide bonds

(Require additional enzymes)

23

Cutting/modifying sugars on (X) residues, that were added in the ER, is done in which organelle?

X = Asn
Golgi

24

When lysosomal hydrolase precursor enters golgi, (glucose/mannose) is attached.

Mannose - glucose trimmed off

25

(Cis/trans) golgi is closer to RER.

Cis

26

Lysosome precursor undergoes which change in cis golgi?

Addition of phosphorylated sugar to mannose

27

Lysosome precursor undergoes which change in trans golgi?

Removal of sugar from phosphorylated sugar complex that was added to mannose in cis-golgi (uncovering signal)

28

Lysosomal storage diseases are usually results of:

deficient or dysfunctional enzymes (thus, buildup of toxic metabolites)

29

How/when do mitochondrial proteins transport into the organelle?

Post-translationally; signal peptide binds receptor on outer mito membrane and complex forms to translocate protein to matrix

30

T/F: There are no molecules that can simply diffuse across the nuclear membrane.

False - very small molecules can

31

(X) proteins make up nuclear pores.

X = Nup (nucleoporins)

32

(X) form the nucleus diffusion barrier as well as the (Y).

X = FG nups
Y = nuclear basket

33

(X) bind nuclear transport receptors, aka (Y), and regulate their entry into nucleus.

X = FG nups
Y = importins

34

T/F: Importins themselves enter the nucleus to drop off cargo (nuclear protein).

True

35

The nuclear lamina is located on (X) and made up of (Y).

X = inside of nuclear envelope
Y = lamin proteins

36

Nuclear lamina functions:

1. stabilize nuclear structure
2. Anchor nuclear pores