GENE-EXPRESSION OF A PROTEIN, JB70, RELATED TO RAT ALPHA(1)-ACID GLYCOPROTEIN IN EUGLENA-GRACILIS

Antibodies directed against rat alpha 1-acid glycoprotein (AGP) recogn ize a 70 kDa antigen, designated JB70, present in extracts of achlorop hyllous Euglena gracilis cells as well as in their culture medium. By using a-dimensional electrophoresis, JB70 appears to be composed of tw o acidic polypeptides. Additionally, Northern blot analysis reveals th e presence in E. gracilis cells of a 2.3 kb mRNA hybridizing with a cD NA probe specific for rat AGP mRNA. Moreover, elevated mRNA levels are detected in dexamethasone-treated E. gracilis cells, indicating a res ponse to this inducer similar to that observed for hepatic AGP. These results strongly suggest that polypeptides closely related to hepatic rat AGP are expressed in E. gracilis cells. They also indicate that, l ike other gene families implicated in natural defense processes such a s heat-shock protein and metallothionein genes, the AGP gene appears t o be conserved down to this early diverging eucaryote. (C) 1997 Academ ic Press.