PAH

PAH is a member of the biopterin-dependent aromatic amino acid hydroxylase protein family. The encoded phenylalanine hydroxylase enzyme hydroxylates phenylalanine to tyrosine and is the rate-limiting step in phenylalanine catabolism. Deficiency of this enzyme activity results in the autosomal recessive disorder phenylketonuria.

Full Name

Phenylalanine Hydroxylase

Function

Catalyzes the hydroxylation of L-phenylalanine to L-tyrosine.

Biological Process

Catecholamine biosynthetic process1 PublicationNAS:BHF-UCL
Cellular amino acid biosynthetic processManual Assertion Based On ExperimentTAS:ProtInc
L-phenylalanine catabolic processIEA:UniProtKB-UniPathway
Neurotransmitter biosynthetic process1 PublicationNAS:BHF-UCL
Tyrosine biosynthetic processManual Assertion Based On ExperimentIBA:GO_Central

Cellular Location

Cytosol

Involvement in disease

Phenylketonuria (PKU):
Autosomal recessive inborn error of phenylalanine metabolism, due to severe phenylalanine hydroxylase deficiency. It is characterized by blood concentrations of phenylalanine persistently above 1200 mumol (normal concentration 100 mumol) which usually causes mental retardation (unless low phenylalanine diet is introduced early in life). They tend to have light pigmentation, rashes similar to eczema, epilepsy, extreme hyperactivity, psychotic states and an unpleasant 'mousy' odor.
Non-phenylketonuria hyperphenylalaninemia (Non-PKU HPA):
Mild form of phenylalanine hydroxylase deficiency characterized by phenylalanine levels persistently below 600 mumol, which allows normal intellectual and behavioral development without treatment. Non-PKU HPA is usually caused by the combined effect of a mild hyperphenylalaninemia mutation and a severe one.
Hyperphenylalaninemia (HPA):
Mildest form of phenylalanine hydroxylase deficiency.

PTM

Phosphorylation at Ser-16 increases basal activity and facilitates activation by the substrate phenylalanine.