ubiquitiniinivälitys
Ubiquitiniinivälitys, often translated as ubiquitination or ubiquitinylation, is a critical post-translational modification in eukaryotic cells. It involves the covalent attachment of a small protein called ubiquitin to a target protein. This process is mediated by a cascade of three enzymes: E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin ligase). The E1 enzyme activates ubiquitin, which is then transferred to an E2 enzyme. Finally, the E3 ligase provides specificity, recognizing the target protein and facilitating the transfer of ubiquitin from the E2 to the substrate.
Ubiquitiniinivälitys can occur as a single ubiquitin molecule (monoubiquitination) or as chains of ubiquitin molecules (polyubiquitination).