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Flashcards in MCM Final Deck (170)
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1

This protein sorting pathway is used for proteins destined for cytosol, mitochondria, nucleus, and peroxisomes

Cytoplasmic

2

This protein sorting pathway synthesizes proteins destined for the ER, lysosomes, plasma membranes, and for secretion

Secretory pathway

3

What is the protein sorting signal that, when present, destines proteins for the cytoplasm

> Trick question. No sorting signal for this destination.

4

What is the protein sorting signal that, when present, destines proteins for the mitochondria

A hydrophobic alpha helix

5

What is the protein sorting signal that, when present, destines proteins for the nucleus

Terminal Lys/Arg repeats

6

What is the protein sorting signal that, when present, destines proteins for the lysosome

M6P

7

What is the protein sorting signal that, when present, destines proteins for a secretory vesicle

Trp rich domain (absent of retention motifs too)

8

What is the protein sorting signal that, when present, destines proteins to stay in the ER

KDEL

9

What disease is caused by a defect in the enzyme required to tag proteins with an M6P signal?

I cell disease. Proteins (hydrolases to be specific) that should be sent to the lysosome are instead packaged for export from the cell and this causes release of harmful enzymes into the blood. Yikes.

10

Proteins sent to the mitochondria are recognized by what mitochondrial membrane transporters?

TIM and TOM

11

How are unfolded proteins protected in the mitochondria?

Binding to chaperones does the trick (HSP70 specifically)

12

How do nuclear proteins enter that membrane bound organelle?

Via specific nuclear pores

13

Large proteins destined for the nucleus require a nuclear localization signal which includes four basic residues. Which amino acids are present here?

Lys, Arg

14

Name the segment of a protein synthesized for secreting that binds ER targeting signal and then the ribosome during translation

Signal recognition particle

15

What is used to tether the ribosome/mRNA/peptide complex together (also causes temporary halt in translation)

Signal recognition particle (SRP)

16

Where do proteins undergo post-translational modifications?

ER or Golgi

17

When a protein contains an ER localization signal, that signal binds the SRP which will then bind what on the RER membrane?

SRP receptor protein

18

What confirmation will small proteins spontaneously assume

Native conformation

19

What could happen when large proteins fold without the help of chaperones

Aggregation or proteolysis

20

What is the term for a protein containing a barrel shaped compartment that admits unfolded proteins and catalyzes their folding? Does this require ATP?

Chaperonins, yes it is ATP dependent

21

What is the post translational process that converts inactive forms to active enzymes

Proteolytic cleavage

22

What are the 3 possible post translational protein modifications

Glycosylation, phosphorylation, disulfide bond formation

23

What post translational modification Occurs on extracellular proteins only

Glycosylation

24

What post translational modification can be either O linked or N linked

Glycosylation

25

What amino acids serve as binding sites for an O linked glycosylation of a protein post translationally

hydroxyl group of Ser or thr

26

What amino acids serve as binding sites for an N linked glycosylation of a protein post translationally

Amino group of Asn

27

What type of bond is formed with the addition of a glycosidic post translational modification

Ester

28

Disulfide bonds form between what functional group of cysteine residues?

Thiol (-SH)

29

Formation and reorganization of disulfide bonds occurs where

ER lumen

30

Beta cells of the pancreas produce what 20 residue peptide?

Preproinsulin