Lesson plan
TIM/TOM complex
The TIM/TOM complex is a protein complex in cellular biochemistry which translocates proteins produced from nuclear DNA through the mitochondrial membrane for use in oxidative phosphorylation. In enzymology, the complex is described as a mitochondrial protein-transporting ATPase ( ), or more systematically ATP phosphohydrolase (mitochondrial protein-importing), as the TIM part requires ATP hydrolysis to work. Only 13 proteins necessary for a mitochondrion are actually coded in mitochondrial DNA. The vast majority of proteins destined for the mitochondria are encoded in the nucleus and synthesised in the cytoplasm. These are tagged by an N-terminal or/and a C-terminal signal sequence. Following transport through the cytosol from the nucleus, the signal sequence is recognized by a receptor protein in the translocase of the outer membrane (TOM) complex. The signal sequence and adjacent portions of the polypeptide chain are inserted in the TOM complex, then begin interaction with a translocase of the inner membrane (TIM) complex, which are hypothesized to be transiently linked at sites of close contact between the two membranes. The signal sequence is then translocated into the matrix in a process that requires an electrochemical hydrogen ion gradient across the inner membrane.…
Article summary
The TIM/TOM complex is a protein complex in cellular biochemistry which translocates proteins produced from nuclear DNA through the mitochondrial membrane for use in oxidative phosphorylation. In enzymology, the complex is described as a mitochondrial protein-transporting ATPase ( ), or more systematically ATP phosphohydrolase (mitochondrial protein-importing), as the TIM part requires ATP hydrolysis to work. Only 13 proteins necessary for a mitochondrion are actually coded in mitochondrial DNA. The vast majority of proteins destined for the mitochondria are encoded in the nucleus and synthesised in the cytoplasm. These are tagged by an N-terminal or/and a C-terminal signal sequence. Following transport through the cytosol from the nucleus, the signal sequence is recognized by a receptor protein in the translocase of the outer membrane (TOM) complex. The signal sequence and adjacent portions of the polypeptide chain are inserted in the TOM complex, then begin interaction with a translocase of the inner membrane (TIM) complex, which are hypothesized to be transiently linked at sites of close contact between the two membranes. The signal sequence is then translocated into the matrix in a process that requires an electrochemical hydrogen ion gradient across the inner membrane.…
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.