Kinnase

Kinnase, a term found in some languages for enzymes that catalyze phosphorylation, refers to what is commonly called kinases in English. These enzymes transfer a phosphate group, usually from ATP, to specific substrates, most often proteins, lipids, or sugars. This phosphorylation alters the activity, interactions, localization, or stability of the target, enabling intricate regulation of cellular processes.

Kinases are broadly classified into protein kinases, lipid kinases, and sugar kinases. Protein kinases constitute the largest group and are further divided by substrate preference into serine/threonine kinases, tyrosine kinases, and dual-specificity kinases. Lipid and sugar kinases act on lipid or carbohydrate substrates, respectively. Within protein kinases, many function as part of signaling cascades, receiving inputs from receptors or other enzymes and conveying signals through phosphorylation networks.

The catalytic mechanism typically involves binding of ATP and substrate in a conserved catalytic core, often requiring cofactors such as Mg2+. The transfer of the terminal phosphate group induces conformational changes that regulate substrate activity. Kinases are regulated at multiple levels, including allosteric sites, subcellular localization, scaffold proteins, and feedback phosphorylation.

Physiological roles are diverse, ranging from cell cycle control and metabolism to development and synaptic signaling. Dysregulation of kinases is linked to diseases such as cancer, diabetes, and neurodegenerative disorders. Because of their central role in signaling, kinases are major drug targets; kinase inhibitors are used in cancer therapy and other conditions, with notable examples including inhibitors targeting receptor and non-receptor kinases.

See also: phosphorylation, ATP, phosphatase.