[1] It displays specificity for phosphothreonine-containing epitopes but will also recognise phosphotyrosine with relatively high affinity.

It spans approximately 80-100 amino acid residues folded into an 11-stranded beta sandwich, which sometimes contains small helical insertions between the loops connecting the strands.

[2] To date, genes encoding FHA-containing proteins have been identified in eubacterial, eukaryotic and archaeal genomes.

[3] In these activities, PNKP acts both as a kinase and a phosphatase in the ligation of DNA ends.

These activities, acting together, prepare single-strand breaks with damaged termini for ligation.