BIOM20001 Lecture 30: 30 Molecular Traffic in the Cell I Cytosol to Nucleus, Mitochondria and ER lumen B
Document Summary
Protein translocators move mitochondrial proteins through both membranes. Cargo proteins bound to chaperones to stop them from folding. These are presented to receptors associated with translocator proteins on membrane. Tom complex (om=outer membrane)- transport through outer membrane. Combination of tom and sam complexes insert proteins into outer membrane. Combination of tom and tim complexes insert proteins into inner membrane and matrix. Tim23 works with tom to send proteins into matrix. Tim22 works with tom to incorporate into inner membrane. Oxa complex inserts mitochondrial genome derived proteins into inner membrane. Signal sequence of precursor protein binds to receptor associated with tom complex. Tom complex aligns with tim complex, protein then threaded through both, and translocated to the matrix. In the matrix, signal sequence is cleaved by a signal peptidase and the protein is folded and incorporated. Molecules incorporated into membranes also have their signal sequences cleaved. Not as well understood but does involve translocator proteins which require activation.
