BCMB30004 Lecture Notes - Lecture 16: Presenilin, Epsin, Amyloid Precursor Protein Secretase
30 Jul 2018
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* ubiquitin is a tag that modifies proteins. * ubiquitin is a small protein: 76 amino acids, 8. 5 kda. * ubiquitin attaches to proteins via a covalent bond. Ubiquitin c-terminal glycine (carboxyl group) attaches to a lysine (amino group) of target protein to form isopeptide bond. * there is covalent attachment of ubiquitin to the substrate protein. * ubiquitin was discovered when researchers were asking why some proteins in the cell were degraded/destroyed while others were spared. So, there is a selective process on which proteins the cell destroys and which proteins the cell keeps alive. * summary of researchers = attachment of ubiquitin to proteins promote their degradation. What are the consequences of ubiquitin attachment to a protein: degradation: this occurs via the proteasome & lysosomal proteases, altered protein trafficking, signalling scaffolds. * three steps: activation, conjugation, ligation: activation: e1 enzyme:
