This domain family is found in bacteria, and is approximately 40 amino acids in length. The family is found in association with Pfam:PF00775. There are two completely conserved residues (Y and R) that may be functionally important. This family is the N terminal region of the beta subunit of protocatechuate 3,4-dioxidase. This enzyme utilizes a mononuclear, non-heme Fe3+ centre to catalyse metabolic cellular reactions.

1: Crystal structure and resonance Raman studies of protocatechuate 3,4-dioxygenase complexed with 3,4-dihydroxyphenylacetate. Elgren TE, Orville AM, Kelly KA, Lipscomb JD, Ohlendorf DH, Que L Jr; Biochemistry. 1997;36:11504-11513. PMID:9298971