Key enzyme in the degradation of tyrosine. 3-(4-hydroxyphenyl)pyruvate + O2 = CO2 + homogentisate Binds 1 Fe cation per subunit. Amino-acid degradation; L-phenylalanine degradation; acetoacetate and fumarate from L-phenylalanine: step 3/6. Expressed in the hypodermis and intestine. RNAi-mediated knockdown together with fah-1 RNAi rescues the impaired growth and fertility defects in the single fah-1 RNAi mutant. Belongs to the 4HPPD family.