Characterization of phenylalanine hydroxylase from rat kidney

1. Phenylalanine hydroxylase has been purified from rat kidney using an immunoaffinity procedure. 2. SDS-PAGE and immunoblot analysis of the purified enzyme revealed subtle differences in the size and abundance of subunits for the enzyme purified from the kidney compared with enzyme purified from the liver. These differences may be explained on the basis of limited proteolysis of the enzyme, during purification from the kidney. 3. The purified renal enzyme is, like the hepatic enzyme, a target for cyclic AMP-dependent protein kinase action. 4. The extent of phosphorylation of the renal enzyme is stimulated by incubation of isolated kidney tubules in the presence of either dibutyryl-cyclic AMP or the protein phosphatase inhibitor, okadaic acid.