Proteins

Kinases are an important class of enzymes and belong to the large family of phosphotransferases. They are involved in the process of substrate phosphorylation, transferring phosphate groups from high - energy molecules such as ATP to specific low - energy target molecules.

Epigenetic enzymes are a class of enzymes that play a crucial role in epigenetics. They regulate gene expression by chemically modifying DNA, histones, etc., without changing the base sequence of DNA. Epigenetic enzymes play an indispensable role in numerous biological processes.

Inside cells, phosphatases play important regulatory and catalytic roles. They can catalyze important reactions in multiple metabolic pathways, regulate the production and consumption of intracellular metabolites, and ensure the normal progress of chemical reactions in cells.

To deal with the threats posed by DNA damage, cells have evolved multiple mechanisms, collectively known as the DNA damage response (DDR), which signal the existence of damage and promote damage repair. Endogenous factors or exogenous factors can all cause DNA damage.

Proteases (also known as proteolytic enzymes or peptidases) refer to enzymes that can hydrolyze peptide bonds in proteins or polypeptides. Proteases play important roles in many diseases and biological processes, such as fetal and postnatal development, reproduction, signal transduction, immune response, and cancer.

The ubiquitination process is usually mediated by the ubiquitin - proteasome system (UPS). In the ubiquitin - proteasome system, there are several key components: ubiquitin, ubiquitin - activating enzyme (E1), ubiquitin - conjugating enzyme (E2), ubiquitin - protein ligase (E3), deubiquitinating enzyme (DUB) and proteasome.