Ubiquitiinijärjestelmä

Ubiquitiinijärjestelmä refers to the ubiquitin-proteasome system (UPS) in Finnish. This is a crucial cellular pathway responsible for the regulated degradation of proteins. It involves two main components: ubiquitin, a small regulatory protein, and the proteasome, a large protein complex.

The process begins with the attachment of ubiquitin molecules to a target protein, a process known as ubiquitination. This tagging action is carried out by a cascade of enzymes, including ubiquitin-activating enzymes (E1), ubiquitin-conjugating enzymes (E2), and ubiquitin ligases (E3). The E3 ligases play a key role in determining the specificity of the system, recognizing and binding to specific substrate proteins.

Once a protein is polyubiquitinated, meaning it has a chain of ubiquitin molecules attached, it becomes a signal for degradation. The ubiquitinated protein is then recognized by the 26S proteasome. The proteasome unfolds the target protein and feeds it into its central core, where it is broken down into small peptides.

The ubiquitin-proteasome system is vital for a wide range of cellular functions, including cell cycle progression, DNA repair, immune response, and the removal of misfolded or damaged proteins. Dysregulation of the UPS has been implicated in various diseases, such as cancer, neurodegenerative disorders, and autoimmune diseases, making it a significant area of research in cell biology and medicine.