Protein Turnover and Degradation

Question 1

Protein turnover

Answer 1

The continuous degradation and re-synthesis of all cellular proteins

Question 2

What affects the rate of protein turnover?

Answer 2

Tissue damage

Severe burns

Question 3

Lysosomal breakdown of proteins

Answer 3

Carried out in the reticulo-endothelial system of the liver (sinusoidal cells, Kupffer cells and pit cells)

Question 4

Lysosomal breakdown- sinusoidal epithelial cells

Answer 4

Remove soluble proteins from the blood through sieve plates on their luminal surface (fibrin, fibrin degradation products, collagen and IgG complexes)
Once in the liver, these proteins these proteins are fused into lysosomes containing lysozyme

Question 5

Kupffer cell sin Lysosal protein degradation

Answer 5

Livers resident macrophages. Phagocyose particular matter, packaging them into phagosomes in the cell which contains hydrolytic enzymes which break the protein down into an amino acid

Question 6

Ubiquitin-Proteasome Pathway

Answer 6

Occurs in cytoplasm and degradation is a selective process.
Proteins can be targetted from protein degradation by the attachment of small peptide called ubiquitin to the protein. This peptide directs the protein to a protein complex called a proteasome, which unfolds the protein and breaks it down into small peptides