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International Journal of Medical Sciences

Int J Biol Sci 2007; 3:237-241 ©Ivyspring International Publisher

Research Paper

Tyrosine Sulfation of Statherin

C. Kasinathan¹, N. Gandhi¹, P. Ramaprasad¹, P. Sundaram², N. Ramasubbu¹

1. Oral Biology, NJ Dental School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103-2400, USA.
2. Current address: Recombinant Technologies LLC, 5 Science Park at Yale, New Haven, CT 06511, USA.

Abstract

Tyrosylprotein sulfotransferase (TPST), responsible for the sulfation of a variety of secretory and membrane proteins, has been identified and characterized in submandibular salivary glands (William et al. Arch Biochem Biophys 1997; 338: 90-96). In the present study we demonstrate the sulfation of a salivary secretory protein, statherin, by the tyrosylprotein sulfotransferase present in human saliva. Optimum statherin sulfation was observed at pH 6.5 and at 20 mm MnCl₂. Increase in the level of total sulfation was observed with increasing statherin concentration. The K_m value of tyrosylprotein sulfotransferase for statherin was 40 μM. Analysis of the sulfated statherin product on SDS-polyacrylamide gel electrophoresis followed by autoradiography revealed ³⁵S-labelling of a 5 kDa statherin. Further analysis of the sulfated statherin revealed the sulfation on tyrosyl residue. This study is the first report demonstrating tyrosine sulfation of a salivary secretory protein. The implications of this sulfation of statherin in hydroxyapatite binding and Actinomyces viscosus interactions are discussed.

Keywords: Saliva, statherin, tyrosine sulfation