Ubiquitination is primarily used to target proteins for what process?

Ubiquitination is a critical post-translational modification that primarily functions to mark proteins for proteasomal degradation. This process involves the attachment of ubiquitin, a small regulatory protein, to lysine residues on the target protein. Once a protein is ubiquitinated, it is recognized and processed by the proteasome, a large proteolytic complex that degrades the tagged proteins into smaller peptides.

This mechanism serves important cellular functions, including the regulation of protein levels, the removal of damaged or misfolded proteins, and the modulation of various cellular processes. It allows the cell to maintain homeostasis and respond to stress by selectively degrading proteins that are no longer needed or potentially harmful.

Other processes such as translation, phosphorylation, and glycosylation are distinct and involve entirely different biochemical pathways and mechanisms. Translation refers to the synthesis of proteins from mRNA, phosphorylation is the addition of phosphate groups to proteins to alter their function or activity, and glycosylation is the process of adding carbohydrate moieties to proteins. Therefore, ubiquitination is specifically and primarily linked to targeting proteins for degradation via the proteasome.