Characterization of sites of tyrosine sulfation in proteins and criteria for predicting their occurrence

A wide variety of secretory proteins have recently been found to undergo post-translational sulfation of specific tyrosine residues. Here, amino acid sequences surrounding known sulfation sites in proteins are analyzed in order to identify factors which determine the specificity of sulfation. Several distinctive features of sulfation sites are identified, including: 1) abundance of acidic amino acid residues, 2) lack of basic residues, 3) low hydropathy, 4) absence of neighboring cysteine residues, 5) lack of extended secondary structure. Rules are proposed for predicting likely sites of sulfation based on the amino acid sequence of a protein.