title: Identification and localization of ERD2 in the malaria parasite Plasmodium falciparum: separation from sites of sphingomyelin synthesis and implications for organization of the Golgi.
abstract: The ERD2 gene product in mammalian cells and yeast is a receptor required for protein retention in the endoplasmic reticulum (ER); immunolocalization studies indicate that the protein is concentrated in the cis Golgi. We have identified a homologue of ERD2 in the malaria parasite, Plasmodium falciparum (PfERD2). The deduced protein sequence is 42% identical to mammalian and yeast homologues and bears striking homology in its proposed tertiary structure. PfERD2 is tightly confined to a single focus of staining in the perinuclear region as seen by indirect immunofluorescence. This is redistributed by brefeldin A (BFA) to a diffuse pattern similar to that of parasite BiP, a marker for the ER; removal of the drug results in recovery of the single focus, consistent with the localization of PfERD2 to the parasite Golgi and its participation in a retrograde transport pathway to the ER. Sphingomyelin synthesis is a second resident activity of the cis Golgi whose organization is sensitive to BFA in mammalian cells. Within the parasite it again localizes to a perinuclear region but does not reorganize upon BFA treatment. The results strongly suggest that these two activities are in distinct compartments of the Golgi in the malaria parasite.
authors.affiliation: Department of Microbiology and Immunology, Stanford University School of Medicine 94305-5402.
authors.forename: H G
authors.initials: HG
authors.lastname: Elmendorf
authors.forename: K
authors.initials: K
authors.lastname: Haldar
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D001483:Base Sequence; D020126:Brefeldin A; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000378:metabolism*; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010963:Plasmodium falciparum / Q000378:metabolism*; D015800:Protozoan Proteins; D018000:Receptors, Peptide; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013109:Sphingomyelins / Q000096:biosynthesis*
chemical_list: D000913:Antibodies, Protozoan; D003517:Cyclopentanes; C489305:ERD2 protein, Plasmodium; C064922:ERD2 protein, S cerevisiae; D008565:Membrane Proteins; D009838:Oligodeoxyribonucleotides; D015800:Protozoan Proteins; D018000:Receptors, Peptide; D029701:Saccharomyces cerevisiae Proteins; D013109:Sphingomyelins; D020126:Brefeldin A