title: Effect of the 1-methyl-4-phenylpyridinium ion on phosphorylation of tyrosine hydroxylase in rat pheochromocytoma PC12h cells.
abstract: Effects of the 1-methyl-4-phenylpyridinium ion (MPP+) on DOPA formation and phosphorylation of tyrosine hydroxylase (TH) of rat pheochromocytoma PC12h cells were examined after the cells were cultured with MPP+. DOPA formed from endogenous tyrosine in PC12h cells after a 3-day culture with 100 microM MPP+ was decreased to less than 50% as compared to that in the control cells cultured without MPP+. Kinetical study showed that two apparent forms of TH with different Km existed in the cells cultured with 100 microM MPP+ but one form in that of control. Incorporation of radioactive phosphate into TH molecule was also reduced to 50% of its control value following a 3-day exposure to 100 microM MPP+. These results suggest that MPP+ acutely inhibits the phosphorylation of TH to decrease cellular DOPA formation.
mesh_terms: D015655:1-Methyl-4-phenylpyridinium; D000310:Adrenal Gland Neoplasms / Q000201:enzymology; D000818:Animals; D004295:Dihydroxyphenylalanine / Q000096:biosynthesis*; D010673:Pheochromocytoma / Q000201:enzymology; D010766:Phosphorylation; D011726:Pyridinium Compounds / Q000494:pharmacology*; D051381:Rats; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D011726:Pyridinium Compounds; D004295:Dihydroxyphenylalanine; D014446:Tyrosine 3-Monooxygenase; D015655:1-Methyl-4-phenylpyridinium