Which enzyme is responsible for transferring a phosphate group from ATP to its substrate?

The enzyme responsible for transferring a phosphate group from ATP to its substrate is a kinase. Kinases play a critical role in cellular metabolism and signaling by catalyzing phosphorylation reactions, where they attach a phosphate group—typically from ATP—to a specific substrate molecule, which often modifies the activity or function of that substrate. This process is essential in regulating various biochemical pathways, including those involved in cell growth, metabolism, and signal transduction.

For instance, in signaling pathways, kinases can activate or deactivate enzymes and receptors, influencing cell responses. The role of kinases is pivotal in numerous biological processes, including metabolism, cell division, and gene expression, making them essential players in maintaining cellular functions.

The other enzymes listed have different functions: proteases break down proteins into smaller peptides or amino acids, lipases are involved in the hydrolysis of fats (lipids), and nucleases degrade nucleic acids like DNA or RNA. These enzymes do not transfer phosphate groups from ATP in the same manner that kinases do.