Protein Modifications

Ubiquitination

Targets proteins for degradation — E1, E2, and E3 ubiquitin-conjugating enzymes

Phosphorylation

Activates or inactivates proteins — Kinases

Glycosylation

Adds sugars to proteins

Lipid modification

Adds lipids to proteins — Lipid transferases

Methylation

Adds methyl groups to proteins

Acetylation

Adds acetyl groups to proteins

SUMOylation

Adds SUMO to proteins

Mono-ubiquitination

Adds a single ubiquitin

Ions (e.g., Fe)

Inherent to the protein

ATP/ADP

Alters protein conformation to turn it “on” or “off” — ATPase / nucleotide binding

GTP/GDP

Alters protein conformation to turn it “on” or “off” — GTPase / nucleotide binding

Proteolysis

Cleaves proteins and can promote function