A putative Sec23 homologue of Plasmodium falciparum is located in Maurer’s clefts

Erythrocytes infected with the human malarial para-site Plasmodium falciparum acquire adhesive propertiesand sequester in the microvasculature. This mechanism,referred to as cytoadhesion, involves the transport of par-asite encoded immunovariant adhesions, collectively calledP. falciparum erythrocyte membrane protein 1 (PfEMP1),to the erythrocyte’s surface, where they act as ligands forcytoadhesive events [1].In cells of higher eukaryotes, intracellular protein trans-port between the various organelles of the endomembranesystem and the plasma membrane is facilitated by vesi-cles. Many, if not all of the vesicles possess a protein coatat their cytosolic surface. The first coat described was theclathrin coat, which is characteristic of endosomal vesicu-lar transport from the plasma membrane to endosomes [2].Distinct from clathrin-coated vesicles are COPI (coat pro-tein I)-coated vesicles[3] that mediate transport steps withinthe Golgi stack and back to the endoplasmic reticulum (ER)[4,5]. The COPI coat was shown to consist of the regulatoryGTPase ARF and seven different protein subunits termed al-pha, beta, beta , gamma, delta, epsilon and zeta [6]. Antero-grade protein traffic from the ER to the Golgi is executed bythe COPII-coated vesicles[7,8]. COPII coats also require ac-tivity of a small GTPase, referred to here as Sar1-activatingcomplex. In addition, two combined complexes consistingof Sec13/31 and Sec23/24 have been described in COPIIprotein-coated vesicles in yeast[9,10], and the structure of