Kinases (also known as phosphotransferases) catalyze phosphorylation. They enable the transfer of the chemically labile γ phosphoryl group from ATP or other nucleoside triphosphates to alcohol or amino group acceptors. Acceptors may be small organic molecules (e.g. glucose) or macromolecules (e.g. proteins) and the phosphorylated form of the acceptor may be more or less active than the non-phosphorylated form. Kinases are widely involved in signal transduction pathways and control complex cellular functions.