Genetics of the mammalian phenylalanine hydroxylase system: I. Isolation of phenylalanine hydroxylase-deficient tyrosine auxotrophs from rat hepatoma cells

1977 ◽  
Vol 3 (5) ◽  
pp. 457-470 ◽  
Author(s):  
K. H. Choo ◽  
R. G. H. Cotton
Keyword(s):  
Phenylalanine Hydroxylase ◽  
Hepatoma Cells ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

Glucocorticoid stimulation of tetrahydrobiopterin levels and phenylalanine hydroxylase activity in rat hepatoma cells

1989 ◽  
Vol 67 (6) ◽  
pp. 293-296 ◽  
Author(s):  
Michael A. Parniak ◽  
Janice Pilkington
Keyword(s):  
Culture Medium ◽  
Phenylalanine Hydroxylase ◽  
Hepatoma Cells ◽  
Rapid Loss ◽  
Maximum Elevation ◽  
Rat Liver Cells ◽  
Important Regulator ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells ◽  
Stimulation Of

Incubation of H4-II-E-C3 rat hepatoma cells with either hydrocortisone or dexamethasone resulted in 3- to 5-fold increases in the levels of both phenylalanine hydroxylase and its essential cofactor, tetrahydrobiopterin. Maximum elevation of phenylalanine hydroxylase was noted after 24 h of incubation, whereas significant increases in tetrahydrobiopterin were found only after 48 h exposure of the cells to glucocorticoids. Removal of hormone from the culture medium resulted in rapid loss of cell tetrahydrobiopterin, but a much slower decline in the level of phenylalanine hydroxylase. Thus, although the levels of both phenylalanine hydroxylase and tetrahydrobiopterin in rat hepatoma cells are regulated by glucocorticoids, this regulation is apparently not strictly coordinated. Nevertheless, control of cellular tetrahydrobiopterin levels may be an important regulator of hepatic phenylalanine catabolism since significant increases in the ability of intact rat liver cells to hydroxylate phenylalanine were observed only after 48 h exposure to glucocorticoids, in correlation with increases in cell tetrahydrobiopterin content.Key words: phenylalanine hydroxylase, tetrahydrobiopterin, glucocorticoid, hepatoma cells.

scholarly journals Identification of the insulin receptor tyrosine residues undergoing insulin-stimulated phosphorylation in intact rat hepatoma cells.

1988 ◽  
Vol 263 (1) ◽  
pp. 350-359 ◽  
Author(s):  
H E Tornqvist ◽  
J R Gunsalus ◽  
R A Nemenoff ◽  
A R Frackelton ◽  
M W Pierce ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Hepatoma Cells ◽  
Tyrosine Residues ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells
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