Bio 103 Lecture 7 READINGS Introduction to organelles 5: 165170 General sorting 16: 657659 Sorting o

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Bio 103 Lecture 7READINGSIntroduction
to organelles 5 165-170General sorting 16
657-659Sorting of proteins to mitochondria 16
683-691

• Mitochondria and Protein Transport

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16-1 Major protein sorting pathways
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12-7 (Alberts) Road map of protein traffic
Topology 1. Gatedcyto to cyto 2.
Transmembrane cyto to exo 3. Vesicular exo to
exo
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Mitochondria and Protein Transport - Overview

• Protein sorting pathways
• Mitochondrial targeting sequence
• Energy input for mitochondrial import
• Mitochondrial import requires receptors and
  translocons
• Transport of proteins into mitochondrial
  subcompartments

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12-4 (Alberts) Hypothetical evolution
membrane-bound organelles
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12-22 (Alberts) Subcompartments of mitochondria

• Consider transport to
• Matrix (16-26)
• Inner mito membrane (16-29)
• Intermembrane space (16-30)

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Mitochondria and Protein Transport

• Protein sorting pathways
• Secretory ER, Golgi, plasma membrane or
  lysosomes
• Non-secretory nucleus, mitochondria
• Mitochondrial targeting sequence
• Amphipathic N-terminus sequence (20-50 residues
  long)
• Signal sequence forms helix with positively
  charged aa on one side, hydrophobic aa on the
  other side of the helix

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12-23 (Alberts) Mitochondrial protein
import-matrix
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Mitochondria and Protein Transport

• Protein sorting pathways
• Mitochondrial targeting sequence
• Energy input for mitochondrial import
• Removal of chaperone protein (cytosolic hsp70)
  requires ATP
• Translocation requires H gradient
• Removal of mitochondrial hsp70 requires ATP

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12-27 (Alberts) Role of energy in the import of
proteins into mitochondria
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Mitochondria and Protein Transport

• Protein sorting pathways
• Mitochondrial targeting sequence
• Energy input for mitochondrial import
• Mitochondrial import requires receptors and
  translocons
• Tom proteins translocon of the outer membrane
• Tim proteins translocon of the inner membrane
• Transport of proteins into mitochondrial
• Matrix (Fig 16-26)
• Inner membrane (Fig 16-29)
• Intermembrane space (Fig 16-30)

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16-26 Mitochondrial protein import-matrix
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16-29 Mitochondrial protein import-inner membrane
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16-30 Mitochondrial protein import-intermembrane
space