PLASMODIUM-YOELII - BREFELDIN A-SENSITIVE PROCESSING OF PROTEINS TARGETED TO THE RHOPTRIES

We have shown that a family of high-molecular-mass proteins can be det ected in lysates of parasitized erythrocytes using antibodies specific for a Plasmodium yoelii rhoptry protein. When these polypeptides are biosynthetically labeled in the presence of brefeldin A or at 15 degre es C, their electrophoretic mobility on polyacrylamide gels is decreas ed. Removal of the drug restores the size of the polypeptides to that in the absence of the drug. These results indicate that the proteins u ndergo a processing event, most probably a proteolytic cleavage, which is inhibited by brefeldin A and low temperature. The data suggest tha t the proteins are moved by secretory transport from the endoplasmic r eticulum through a functional Golgi to the rhoptry organelles. (C) 199 4 Academic Press, Inc.