Genetics of mammalian phenylalanine hydroxylase system. IV. Evidence of phenylalanine hydroxylase in a cultured human hepatoma cell line.
We report here te identification of a cultured human hepatoma cell line which possesses an active phenylalanine hydroxylase system. Phenylalanine hydroxylation was established by growth of cells in a tyrosine-free medium and by the ability of a cell-free extract to convert [14C]phenylalanine to [14C]tyrosine in an enzyme assay system. This enzyme activity was abolished by the presence in the assay system of p-chlorophenylalanine but no significant effect on the activity was observed with 3-iodotyrosine and 6-fluorotryptophan. Use of antisera against pure monkey or human liver phenylalanine hydroxylase has detected a cross-reacting material in this cell line which is antigenically identical to the human liver enzyme. Phenylalanine hydroxylase purified from this cell line by affinity chromatography revealed a multimeric molecular weight (estimated 275,000) and subunit molecular weights (estimated 50,000 and 49,000) which are similar to those of phenylalanine hydroxylase purified from a normal human liver. This cell line  should be a useful tool for the study of the human phenylalanine hydroxylase system.
D000818:Animals; D002460:Cell Line; D002846:Chromatography, Affinity; D006801:Humans; D007700:Kinetics; D008114:Liver Neoplasms, Experimental / Q000201:enzymology*; D010649:Phenylalanine; D010651:Phenylalanine Hydroxylase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
D010649:Phenylalanine; D010651:Phenylalanine Hydroxylase