Proteolysis and ubiquitylation are key and interconnected processes involved in the regulation of protein levels and function within cells. They play crucial roles in various cellular functions, including cell cycle progression, protein quality control, signal transduction, and gene expression. Proteolysis refers to the breakdown of proteins into smaller peptides or amino acids and is an essential process for maintaining protein homeostasis within cells. There are two main pathways of proteolysis: lysosomal degradation and the ubiquitin-proteasome system (UPS). Lysosomal degradation involves the transport of proteins to lysosomes, where they are degraded by lysosomal proteases. This pathway is important for the turnover of long-lived proteins, clearance of misfolded or damaged proteins, and the degradation of extracellular proteins taken up by phagocytosis. In this pathway, proteins are first engulfed into vesicles called autophagosomes, which then fuse with lysosomes. The lysosomal enzymes degrade the protein constituents into amino acids, which can be recycled for new protein synthesis. Conversely, the UPS pathway is responsible for a more selective degradation of short-lived and/or regulatory proteins. Ubiquitylation is a post-translational modification process where ubiquitin, a small 76 amino acid protein, is covalently linked to target proteins. This process involves a series of enzymatic reactions mediated by three types of enzymes: E1 (ubiquitin-activating enzymes), E2 (ubiquitin-conjugating enzymes), and E3 (ubiquitin ligases).The E1 enzyme activates ubiquitin by forming a thioester bond with its C-terminal glycine residue. Then, the ubiquitin is transferred to the E2 enzyme. Finally, the E3 enzyme recognizes the target protein and facilitates the transfer of ubiquitin from the E2 enzyme to a specific lysine residue on the target protein. This process can be repeated, leading to the addition of multiple ubiquitin molecules, forming a polyubiquitin chain. Ubiquitylation serves as a molecular tag that targets proteins for degradation by the proteasome, a large multi-subunit protease. The polyubiquitin chain provides a recognition signal for the proteasome, which unfolds the ubiquitylated protein and cleaves it into small peptides. These peptides can then be further degraded into amino acids. Ubiquitylation has diverse functions beyond protein degradation. It can regulate protein activity, localization, interactions, and stability. For example, monoubiquitylation can modulate protein-protein interactions or influence subcellular localization. On the other hand, polyubiquitylation with specific linkage types (e.g., K48-linked) typically targets proteins for proteasomal degradation, while other linkage types (e.g., K63-linked) can mediate non-proteolytic functions, such as DNA repair or signalling. Ubiquitylation is a highly regulated process. Deubiquitylating enzymes (DUBs) can remove ubiquitin from proteins, providing a means to reverse the ubiquitylation process and regulate protein stability or function. Additionally, the balance between ubiquitin ligases and deubiquitylating enzymes ensures proper cellular proteostasis and prevents aberrant protein accumulation or degradation. Defects in proteolysis and ubiquitylation have been implicated in the development of numerous diseases, including cancer, neurodegenerative disorders, and autoimmune diseases. Dysregulation of the UPS can lead to the accumulation of abnormal proteins, which can have detrimental effects on cellular function and contribute to disease. We provide a large product range of research reagents for studying proteolysis and ubiquitin, including BRCA1 antibodies, MMP9 antibodies, MMP3 antibodies, MMP9 ELISA Kits, and MMP3 ELISA Kits. Explore our full proteolysis and ubiquitin product range below and discover more, for less. Alternatively, you can explore our Proteasome & Ubiquitin, Proteolytic Enzymes, and Protease Inhibitors product ranges.