title: Plasmodium falciparum Sec24 marks transitional ER that exports a model cargo via a diacidic motif.
abstract: Exit from the endoplasmic reticulum (ER) often occurs at distinct sites of vesicle formation known as transitional ER (tER) that are enriched for COPII vesicle coat proteins. We have characterized the organization of ER export in the malaria parasite, Plasmodium falciparum, by examining the localization of two components of the COPII machinery, PfSec12 and PfSec24a. PfSec12 was found throughout the ER, whereas the COPII cargo adaptor, PfSec24a, was concentrated at distinct foci that likely correspond to tER sites. These foci were closely apposed to cis-Golgi sites marked by PfGRASP-GFP, and upon treatment with brefeldin A they accumulated a model cargo protein via a process dependent on the presence of an intact diacidic export motif. Our data suggest that the cargo-binding function of PfSec24a is conserved and that accumulation of cargo in discrete tER sites depends upon positive sorting signals. Furthermore, the number and position of tER sites with respect to the cis-Golgi suggests a co-ordinated biogenesis of these domains.
authors.affiliation: Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
authors.forename: Marcus C S
authors.initials: MC
authors.lastname: Lee
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Moura
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Miller
authors.forename: David A
authors.initials: DA
authors.lastname: Fidock
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001665:Binding Sites; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D008954:Models, Biological; D010963:Plasmodium falciparum / Q000737:chemistry / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D015800:Protozoan Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D015800:Protozoan Proteins; D033921:Vesicular Transport Proteins