This family consists of proteins predominantly found in bacteria, including Alkaline phosphatase PhoX from Pseudomonas fluorescens (Swiss:Q3K5N8), a phosphomonoesterase with no phosphodiesterase activity. This protein adopts a six-bladed beta-propeller fold, with the active site located at the bottom of the cavity at the centre of the propeller [1].

1: A complex iron-calcium cofactor catalyzing phosphotransfer chemistry. Yong SC, Roversi P, Lillington J, Rodriguez F, Krehenbrink M, Zeldin OB, Garman EF, Lea SM, Berks BC; Science. 2014;345:1170-1173. PMID:25190793