Post-translational hydroxylation of aspartic acid or asparagine [<cite idref="PUB00002475"/>] to formerythro-beta-hydroxyaspartic acid or erythro-beta-hydroxyasparagine has beenidentified in a number of proteins with domains homologous to epidermal growthfactor (EGF). Examples of such proteins are the blood coagulation proteinfactors VII, IX and X, proteins C, S, and Z, the LDL receptor, thrombomodulin,etc. Based on sequence comparisons of the EGF-homology region that containshydroxylated Asp or Asn, a consensus sequence has been identified that seemsto be required by the hydroxylase(s).