Question

Tyrosine hydroxylase (TH) is an enzyme that converts tyrosine to L-Dopa. In your lab, you genetically engineer a mouse that can't make TH. What neurotransmitter system(s) would be affected?

a. serotonin b. dopamine c. norepinephrine d. all of the above e. (b) and (c) only

Answer 1

answer to the above question is:

e.) (b) and (c) only

Tyrosine hydroxylase or tyrosine 3-monooxygenase is the enzyme responsible for catalyzing the conversion of the amino acid L-tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA). It does so using molecular oxygen (O₂), as well as iron (Fe²⁺) and tetrahydrobiopterin as cofactors. L-DOPA is a precursor for dopamine, which, in turn, is a precursor for the important neurotransmitters norepinephrine (noradrenaline) and epinephrine (adrenaline). Tyrosine hydroxylase catalyzes the rate limiting step in this synthesis of catecholamines. In humans, tyrosine hydroxylase is encoded by the TH gene, and the enzyme is present in the central nervous system (CNS), peripheral sympathetic neurons and the adrenal medulla.Tyrosine hydroxylase, phenylalanine hydroxylase and tryptophan hydroxylase together make up the family of aromatic amino acid hydroxylases (AAAHs).