Co-Induction of Tetrahydrobiopterin (BH4) Levels and Tyrosine Hydroxylase Activity in Cultured PC12 Cells
BH4 is the cofactor for Phenylalanine hydroxylase, as well as tyrosine and tryptophan hydroxylases, which are the rate-limiting enzymes in catecholamine (CA) and Serotonin synthesis, respectively. CTP cyclohydrolase (CTP-CH) and sepiapterin reductase (SR) catalyze the initial and final steps in BH4 biosynthesis, respectively. Because no intermediates are detected, CTP-CH is thought to be the rate-limiting enzyme in nonprimate BH4 biosynthesis. In humans, the existence of neopterin in fluids suggests that other enzymes following CTP-CH may also play a regulatory role in BH4 biosynthesis.
KeywordsPC12 Cell Nerve Growth Factor Tyrosine Hydroxylase Vasoactive Intestinal Peptide Phenylalanine Hydroxylase
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