BIOB10H3 Lecture Notes - Lecture 7: Virulence-Related Outer Membrane Protein Family, Mitochondrial Matrix, Intermembrane Space

47 views7 pages
user avatar
Published on 17 Nov 2010
School
UTSC
Department
Biological Sciences
Course
BIOB10H3
Professor
MITOCHONDRIA:
Structure & Function
Mitochondria: origin
-Mitochondria arose from aerobic prokaryotes - phagocytosed by eukaryotes
-Mitochondria can divide within the cell - ^u]}Z}v]o(]]}v_
Mitochondria: structure
-Outer membrane (OMM)
-Inner membrane (cristae) Å two are intermembrane space
-Matrix Å GEL LIKE
-2 membranes
-2 aqueous compartments
Mitochondria structure: OMM Æ The outer mitochondrial
membrane:
-serves as the outer boundary of the organelle
-has ~ 50% protein : 50% lipid ratio
-has a diverse number of proteins that function as enzymes
-several large protein channels t porins
- Not specific & variety of moleciles
-t-pleated sheets
-can allow passage of large number of molecules ((e.g. ATP)
-respond to conditions within the cell Æ E.G. cell stress
Mitochondria structure: IMM
The inner mitochondrial membrane Æ thin folds
-has cristae
-has ~75% protein: 25% lipid ratio
-almost 100 different proteins present and has almost no cholesterol
-is rich in a phospholipid called cardiolipin Æ found in many bacterial membrane
-very impermeable to molecules and has many channels & pumps Æ highly selective
Mitochondria structure: matrix
-gel-like consistency from the high concentration of proteins and DNA
-contains DNA (own genetic material) and ribosomes
-mitochondrial DNA encodes ~ 37 genes in humans
Mitochondrial proteins
-The majority of proteins that function in the mitochondria are encoded by DNA in the cell nucleus
-These proteins are translated on free ribosomes in the cytosol
-They then need to be imported into the mitochondria Æ POST-translational import protein
www.notesolution.com
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 7 pages and 3 million more documents.

Already have an account? Log in
Mitochondria are cellular organelles.
What do you need to target proteins to an organelle? SIGNAL
Mitochondrial proteins: signals for import
Matrix proteins:
Signal = u]}Z}v]o^µv_
-at the N-terminus of proteins: composed of several positively charged residues Æ +
IMM proteins (integral membrane proteins):
Contain internal targeting sequences (poorly defined) and stop- transfer sequences
Mitochondria: importing proteins
-For mitochondrial import, proteins need to be in an unfolded state
-helped by chaperone proteins in the cytosol Æ E.G. HSP 70
-Unfolded proteins then bind to membrane receptors on OMM
-Receptors are located close to large protein channels called TOM complexes
TOM = translocase (or transporter) of the outer membrane
-help to move proteins past the OMM into the intermembrane space
Å Fig 8.47
- bound by chaperone to keep it unfold,
then interact with receptor
Post-translational import of IMM proteins
-proteins delivered to the intermembrane space
then interact with the TIM 22 complex
-TIM = translocase (or transporter) of the
inner membrane
-stop transfer sequence then interacts with channel
and is moved laterally into the IMM
Æ fig. Interact with TIM to inner membrane
-several proteins that are involved in energy
production are imported by this pathway
www.notesolution.com
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 7 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Mitochondria arose from aerobic prokaryotes - phagocytosed by eukaryotes. Mitochondria can divide within the cell - k . Inner membrane (cristae)  two are intermembrane space. Mitochondria structure: omm  the outer mitochondrial membrane: Serves as the outer boundary of the organelle. Has ~ 50% protein : 50% lipid ratio. Has a diverse number of proteins that function as enzymes. Can allow passage of large number of molecules ((e. g. atp) Respond to conditions within the cell  e. g. cell stress. Almost 100 different proteins present and has almost no cholesterol. Is rich in a phospholipid called cardiolipin  found in many bacterial membrane. Very impermeable to molecules and has many channels & pumps  highly selective. Gel-like consistency from the high concentration of proteins and dna. Mitochondrial dna encodes ~ 37 genes in humans. The majority of proteins that function in the mitochondria are encoded by dna in the cell nucleus.