09a: Protein Trafficking Flashcards

1
Q

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

A

True

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2
Q

Proteins translated on cytoplasmic ribosomes are targeted to:

A
  1. Cytoplasm
  2. Mitochondria
  3. Nucleus
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3
Q

Proteins translated on RER ribosomes are targeted to:

A
  1. Cell membrane
  2. Lysosomes
  3. Cell secretion
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4
Q

What’s the power house of protein synthesis?

A

RER

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5
Q

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

A

Primary

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6
Q

Cytoplasmic protein have which signal?

A

No signal

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7
Q

Mitochondrial protein have which signal?

A

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

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8
Q

Nuclear proteins have which signal?

A

Lys-Lys-Lys-Arg-Lys

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9
Q

Membrane proteins have which signal?

A

Core of hydrophobic AA near N terminus

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10
Q

Secretory proteins have which signal?

A

Core of hydrophobic AA near N terminus

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11
Q

Lysosomal proteins have which signal?

A

Mannose-6-P

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12
Q

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

A
X = Signal Recognition Particle
Y = snRNPs (has RNA and protein components)
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13
Q

What’s the function of SRPs?

A

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

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14
Q

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

A

X = signal peptide

SRP binds its receptor on ER membrane

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15
Q

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

A

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

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16
Q

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

A

True - cleaved by signal peptidase

17
Q

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

A
X = stop-transfer 
Y = core of hydrophobic
18
Q

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

A

ER

19
Q

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

A

Golgi

20
Q

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

A

Golgi

21
Q

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

A

X = Asn (X-Ser/Thr)

Mannose

22
Q

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

A
  1. Pro regions
  2. Disulfide bonds

(Require additional enzymes)

23
Q

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

A

X = Asn

Golgi

24
Q

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

A

Mannose - glucose trimmed off

25
Q

(Cis/trans) golgi is closer to RER.

A

Cis

26
Q

Lysosome precursor undergoes which change in cis golgi?

A

Addition of phosphorylated sugar to mannose

27
Q

Lysosome precursor undergoes which change in trans golgi?

A

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

28
Q

Lysosomal storage diseases are usually results of:

A

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

29
Q

How/when do mitochondrial proteins transport into the organelle?

A

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

30
Q

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

A

False - very small molecules can

31
Q

(X) proteins make up nuclear pores.

A

X = Nup (nucleoporins)

32
Q

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

A
X = FG nups
Y = nuclear basket
33
Q

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

A
X = FG nups
Y = importins
34
Q

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

A

True

35
Q

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

A
X = inside of nuclear envelope
Y = lamin proteins
36
Q

Nuclear lamina functions:

A
  1. stabilize nuclear structure

2. Anchor nuclear pores