Cloning and Identification of a New Antimicrobial Protein, Salvic, from Human Salivary Gland

Abstract

From a subtracted cDNA library of human salivary gland a C77-91 gene totally unknown to date was named as Salvic that expresses 46 amino acids peptide (pI=9.45) possessing an antimicrobial activity on E. coli. Salvic is consisted of a typical hydrophobic amino acid rich domain in the N-terminus, a cluster of basic amino acids, carbohydrate attachment sites, a possible transglutaminase catalyzed crosslinking site, and multiple consensus sequences of phosphorylation site in the C-terminus. Western blot analysis using the monospecific antibody to the synthetic Salvic peptide showed strong interacting proteins in the extracts from submandibular gland and parotid saliva, and the immunohistochemical staining detected a strong positive reaction in the cytoplasmic secretory granules of interlobular ductal cells of salivary gland. The Salvic was also distributed in the human sebaceous gland and prostate. These data suggest that the identification of Salvic may add further understanding of greater role of salivary proteins providing innate immunity by protecting and stabilizing the mucosal epithelium in the maintaining homeostasis of oral mucosa.