Molecular Cloning and Homology Modeling of Novel Tyrosylprotein Sulfotransferase of Marine Mollusk

The gene of tyrosylprotein sulfotransferase, which was discovered in mammals, has been widely found in marine mollusk Littorina sitkana. High conservation of this gene indicates the functional importance of TPST in the metabolism of the living world. The cDNA encoding TPST in the mollusk was cloned and sequenced, and the enzyme was assigned on the basis of amino acid sequence similarity as tyrosylprotein sulfotransferase-2 (TPST-2). The putative homology model for the catalytic domain of TPST from L. sitkana was constructed according to crystal structure of the catalytic domain of the human TPST-2. The putative model of dimer structure showed that the active site involved two monomers and the dimer contains two active centers.