ISOLATION AND CHARACTERIZATION OF A GENE EXPRESSED MAINLY IN THE GASTRIC EPITHELIUM, A NOVEL MEMBER OF THE EP37 FAMILY THAT BELONGS TO THE BETA-GAMMA-CRYSTALLIN SUPERFAMILY

EP37 family proteins are non-lens members of the beta gamma-crystallin superfamily, of which expression is observed in integumental tissues of the Japanese newt, Cynops pyrrhogaster, in the present study, a gen e was isolated that has high homology with ep37 and is transcribed mai nly in the gastric epithelial cells and hence designated gep. The pred icted amino acid sequence of the gep cDNA contains four beta gamma-cry stallin motifs in the N-terminal half. as is the case in the integumen tal EP37 proteins. Immunohistochemical analysis showed that GEP protei n was mainly localized on the luminal content of the surface mucous ce lls of the gastric epithelium in both premetamorphic larvae and adults . In addition, GEP protein was also expressed in fundic glands after m etamorphosis. Considering the fact that beta- and gamma-crystallins ar e evolutionarily related to stress-induced proteins, this localization suggests that GEP protein may have an evolutionarily conserved role i n protection against physicochemical stresses, such as physical abrasi on and autodigestion, during assimilation.