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Mitochondria > Lecture4 > Flashcards

Lecture4 Flashcards

1
Q

tim11 pro dimerization ATP synthase

True or false?

A

True

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2
Q

All cristae are dependent on each other and they have some potential.
true or false?

A

false, All cristae in one mt are independent and have different potential.

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3
Q

There is about 901 proteome in mitochondria

true or false?

A

true

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4
Q

44.9% pro present in mt belong to metabolism. true or false?

A

True

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5
Q

In biochemical approach, what will u treat mt with

and it can attach OM pro so u can see the pro degrarded

A

proteinase k

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6
Q

how the biochemistry approach extracts mt works?

A

OM-> proteinase k
IMS -> hypotonic (Swelling) water come inside of mt
Matrix-> proteinase k

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7
Q

The major amount of mt proteins are in OM and IMS

A

False, about 40% in both matrix and IM of mt are the majarity

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8
Q

There are only …. proteins that are encoded by cytosolic ribosomes and … proteins by mtDNA

A

1000, 10

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9
Q 
Say an example for each.
Matrix proteins (....)
IM proteins  (....)
IMS proteins  (....)
OM proteins (....)
A 
Matrix proteins (e. g. TCA cycle)
IM proteins (e. g. Respiratory chain)
IMS proteins (e. g. Cytochrome c)
OM proteins (e. g. Import translocase)
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10
Q

To get the answer to the question: Do mRNAs that encode for mitochondrial proteins localize to mitochondria?
What approach did they use?

A

Post- and Co-translational targeting of

proteins to mitochondria

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11
Q

Biotinylated protein can be purified using…..

A

Streptavidin beads

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12
Q

…. of mRNAs encoding mitochondrial proteins are synthesised on ‘free’ ribosomes
The remaining proteins are synthesised on mitochondrial-bound ribosomes
The only factor proposed to be involved in localisation of mRNAs to mitochondria is the RNA
binding protein ….

A

50% , Puf3

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13
Q

What are The signal sequences for proteins import?

A

1) N-terminal cleavable pre-sequence
2) Cystein motifs
3) Internal targeting
4) signals Beta-barrels

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14
Q

What are the features of N-terminal cleavable pre-sequence?

A 
• 60% of mitochondrial
proteins (IM and Matrix)
• Pre-sequence is ~15-50
amino acids long
• Positively charged
• Amphipathic helix
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15
Q

What are the features of pre-sequence Cystein motifs?

A 
• Small proteins of the
IMS
• Cx3C or Cx9C motifs
• MISS (Mitochondrial-
IMS-sorting signal)
short hydrophobic
sequence and a
cysteine residue
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16
Q

What are the features of Internal targeting signals?

A 
• Found in carrier
proteins of the IM
• Carrier proteins are
bound by Hsp70 and
Hsp90 chaperones
• Chaperones are
involved in targeting
17
Q

What are the features of Beta-barrels?

A

• Outer membrane
proteins
• C-terminal beta-hairpin

18
Q

How does N-terminal cleavable pre-sequence pass through TOM complex?

A 
• Pre-sequence binds Tom20
• Protein is handed over to:
• The cytosolic domain of Tom22
• The Tom40 import channel
• The IMS domain of Tom22
• Increase in substrate affinity is
thought to drive the translocation
• TOM5, 6, and 7 are required for
assembly and stability of TOM
19
Q

What will happen next to Emerging pre-sequences in IMS?

A
  • Emerging pre-sequences are bound by Tim50
  • Tim23 forms import channel
  • Tim21 recruits the supercomplex III-IV
  • Increases local membrane potential and helps translocation
20
Q

Say each function in Tim complex
TIm44=
Tim14 and Tim16=
Mge1=

A
  • Tim44 couples mtHsp70 to TIM complex
    • Tim14 and Tim16 regulate ATP hydrolysis of
    mtHsp70
    +++
    • Mge1 is the nucleotide exchange factor for mtHsp70
21
Q

What are the two hypotheses of mitochondria import power?

A

1) Brownian ratchet -> Trapping of the substrate to prevent backsliding
2) Power stroke -> Active pulling

22
Q

Once Pre-sequence enter to the matrix by Tim complex PreP cleaves off pre-sequence MPP degrades signal sequence
False or True?

A

False, Once Pre-sequence enter to matrix by Tim complex MPP cleaves off pre-sequence PreP degrades signal sequence

23
Q

Lateral release of proteins into the inner membrane is happened by…. signal, ….. binds stop-transfer signal and controls release into the…

A

Stop Signal, Mgr2, inner membrane

24
Q

Tim50 is highly conserved.

F or T?

A

True

25
Q

Tim50 behaves like the protein mge1 and
therfore must have a domain exposed to the IMS and its membrane protein.
T or F?

A

False, Tim50 behaves like the protein Tim23 and

therfore must have a domain exposed to the IMS

26
Q

Expression of Tim50 from a Glucose inducible promoter. T or F?

A

False, Expression of Tim50 from a galactose inducible promoter

27
Q

Tim50 is essential for cell survival

T or F?

A

True

28
Q

Tim50 is not required for the transport of proteins across the inner membrane.

A

False, Tim50 is required for the transport of proteins across the inner membrane

29
Q

The intermembrane space
Answer 1

The mitochondrial inner membrane
Answer 2

The mitochondrial matrix
Answer 3

The outer mitochondrial membrane
Answer 4

A 
The intermembrane space
Answer 1
90
 The mitochondrial inner membrane
Answer 2
360
 The mitochondrial matrix
Answer 3
360
 The outer mitochondrial membrane
Answer 4
90
30
Q

What powers import?

A
  • The membrane potential

* Hsp70

31
Q

What are the functions of oxa1?

A

• Oxa1 exports domain through the IM
• Oxa1 also exports mtDNA encoded
proteins into the inner membrane

Mitochondria (9 decks)

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