In enzymology, a dephospho-[reductase kinase] kinase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are ATP and dephospho-<nowiki/>{[hydroxymethylglutaryl-CoA reductase (NADPH)] kinase}, whereas its two products are ADP and {[hydroxymethylglutaryl-CoA reductase (NADPH)] kinase}.
This enzyme belongs to the family of transferases, specifically those transferring a phosphate group to the sidechain oxygen atom of serine or threonine residues in proteins (protein-serine/threonine kinases). The systematic name of this enzyme class is ATP:dephospho-<nowiki/>{[hydroxymethylglutaryl-CoA reductase (NADPH)] kinase} phosphotransferase. Other names in common use include AMP-activated kinase, AMP-activated protein kinase kinase, hydroxymethylglutaryl coenzyme A reductase kinase kinase, hydroxymethylglutaryl coenzyme A reductase kinase kinase, (phosphorylating), reductase kinase, reductase kinase kinase, and STK30.