is kinase activity molecular_function kinase activity true phosphokinase activity Note that this term encompasses all activities that transfer a single phosphate group; although ATP is by far the most common phosphate donor, reactions using other phosphate donors are included in this term. GO:0016301 Reactome:R-HSA-6788867 Catalysis of the transfer of a phosphate group, usually from ATP, to a substrate molecule. Reactome:R-HSA-6788855