Cyclic GMP (cGMP)-dependent protein kinase (G kinase) can be purified from bovine lung with the combination of ion-exchange chromatography, ammonium sulfate precipitation, and cyclic nucleotide affinity chromatography (1 ). In this chapter, we describe the purification procedure that is routinely used in our laboratory. As a source, the bovine lung seems to be the best material to obtain a large amount of purified sample. However, the procedure described here can be applicable to the purification of G kinase from various mammalian or nonmammalian tissues.
