The FHA domain

Abstract
The forkhead‐associated (FHA) domain is a small protein module recently shown to recognize phosphothreonine epitopes on proteins. It is present in a diverse range of proteins in eukaryotic cells, such as kinases, phosphatases, kinesins, transcription factors, RNA‐binding proteins, and metabolic enzymes. It is also found in a number of bacterial proteins. This suggests that FHA domain‐mediated phospho‐dependent assembly of protein complexes is an ancient and widespread regulatory mechanism.