Genetics of the mammalian phenylalanine hydroxylase system. IV. Evidence of phenylalanine hydroxylase in a cultured human hepatoma cell line

K. H. Choo, R. G.H. Cotton, I. G. Jennings, K. Fowler, D. M. Danks

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We report here the 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.

Original languageEnglish
Pages (from-to)955-968
Number of pages14
JournalBiochemical Genetics
Issue number9-10
Publication statusPublished - 1 Oct 1980
Externally publishedYes


  • cultured human hepatoma
  • phenylalanine hydroxylase

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