title: The polyamine-dependent modulation of phenylalanine hydroxylase phosphorylation state and enzymic activity in isolated liver cells.
abstract: The role of polyamines in the control of phenylalanine hydroxylase phosphorylation state and enzymic activity was investigated. Pre-treatment of liver cells with spermine (1 mM) abolishes the glucagon (1 nM)-stimulated increase in hydroxylase phosphorylation. Concurrently there is a decrease in phenylalanine hydroxylation flux, reflecting decreased enzyme activity; 50% inhibition occurs at approx. 10 microM-spermine. These results are discussed in the context of reports concerning the properties of protein phosphatase 2A.
mesh_terms: D000818:Animals; D005934:Glucagon / Q000494:pharmacology; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D010651:Phenylalanine Hydroxylase / Q000378:metabolism*; D010766:Phosphorylation; D011073:Polyamines / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013096:Spermine / Q000494:pharmacology
chemical_list: D011073:Polyamines; D013096:Spermine; D005934:Glucagon; D010651:Phenylalanine Hydroxylase