Lecture4 Flashcards
tim11 pro dimerization ATP synthase
True or false?
True
All cristae are dependent on each other and they have some potential.
true or false?
false, All cristae in one mt are independent and have different potential.
There is about 901 proteome in mitochondria
true or false?
true
44.9% pro present in mt belong to metabolism. true or false?
True
In biochemical approach, what will u treat mt with
and it can attach OM pro so u can see the pro degrarded
proteinase k
how the biochemistry approach extracts mt works?
OM-> proteinase k
IMS -> hypotonic (Swelling) water come inside of mt
Matrix-> proteinase k
The major amount of mt proteins are in OM and IMS
False, about 40% in both matrix and IM of mt are the majarity
There are only …. proteins that are encoded by cytosolic ribosomes and … proteins by mtDNA
1000, 10
Say an example for each. Matrix proteins (....) IM proteins (....) IMS proteins (....) OM proteins (....)
Matrix proteins (e. g. TCA cycle) IM proteins (e. g. Respiratory chain) IMS proteins (e. g. Cytochrome c) OM proteins (e. g. Import translocase)
To get the answer to the question: Do mRNAs that encode for mitochondrial proteins localize to mitochondria?
What approach did they use?
Post- and Co-translational targeting of
proteins to mitochondria
Biotinylated protein can be purified using…..
Streptavidin beads
…. 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 ….
50% , Puf3
What are The signal sequences for proteins import?
1) N-terminal cleavable pre-sequence
2) Cystein motifs
3) Internal targeting
4) signals Beta-barrels
What are the features of N-terminal cleavable pre-sequence?
• 60% of mitochondrial proteins (IM and Matrix) • Pre-sequence is ~15-50 amino acids long • Positively charged • Amphipathic helix
What are the features of pre-sequence Cystein motifs?
• Small proteins of the IMS • Cx3C or Cx9C motifs • MISS (Mitochondrial- IMS-sorting signal) short hydrophobic sequence and a cysteine residue
What are the features of Internal targeting signals?
• Found in carrier proteins of the IM • Carrier proteins are bound by Hsp70 and Hsp90 chaperones • Chaperones are involved in targeting
What are the features of Beta-barrels?
• Outer membrane
proteins
• C-terminal beta-hairpin
How does N-terminal cleavable pre-sequence pass through TOM complex?
• 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
What will happen next to Emerging pre-sequences in IMS?
- Emerging pre-sequences are bound by Tim50
- Tim23 forms import channel
- Tim21 recruits the supercomplex III-IV
- Increases local membrane potential and helps translocation
Say each function in Tim complex
TIm44=
Tim14 and Tim16=
Mge1=
- Tim44 couples mtHsp70 to TIM complex
• Tim14 and Tim16 regulate ATP hydrolysis of
mtHsp70
+++
• Mge1 is the nucleotide exchange factor for mtHsp70
What are the two hypotheses of mitochondria import power?
1) Brownian ratchet -> Trapping of the substrate to prevent backsliding
2) Power stroke -> Active pulling
Once Pre-sequence enter to the matrix by Tim complex PreP cleaves off pre-sequence MPP degrades signal sequence
False or True?
False, Once Pre-sequence enter to matrix by Tim complex MPP cleaves off pre-sequence PreP degrades signal sequence
Lateral release of proteins into the inner membrane is happened by…. signal, ….. binds stop-transfer signal and controls release into the…
Stop Signal, Mgr2, inner membrane
Tim50 is highly conserved.
F or T?
True
Tim50 behaves like the protein mge1 and
therfore must have a domain exposed to the IMS and its membrane protein.
T or F?
False, Tim50 behaves like the protein Tim23 and
therfore must have a domain exposed to the IMS
Expression of Tim50 from a Glucose inducible promoter. T or F?
False, Expression of Tim50 from a galactose inducible promoter
Tim50 is essential for cell survival
T or F?
True
Tim50 is not required for the transport of proteins across the inner membrane.
False, Tim50 is required for the transport of proteins across the inner membrane
The intermembrane space
Answer 1
The mitochondrial inner membrane
Answer 2
The mitochondrial matrix
Answer 3
The outer mitochondrial membrane
Answer 4
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
What powers import?
- The membrane potential
* Hsp70
What are the functions of oxa1?
• Oxa1 exports domain through the IM
• Oxa1 also exports mtDNA encoded
proteins into the inner membrane
