The intracellular breakdown pathways of proteins are classified into two main types:
- Lysosomal protein degeneration (Figure 1)
- Ubiquitin-dependent protein degeneration (Figure 2)
Lysosomal protein degradation
- occurs at acidic pH
- Lysosomes are full of various hydrolyzes (proteases, nucleases)
- Degradation of extra- and intracellular wrong protein, phagocytosed microorganisms
- Proteolytic enzymes of the lysosomes are:
- cathepsins
- cystein proteinases
- aspartyl proteinases
- amino and carboxypeptidases