title: Cis and trans factors involved in apicoplast targeting in Toxoplasma gondii.
abstract: Ribosomal subunit protein 9 (rps9) is a nuclearly encoded protein that resides in the apicoplast organelle of Toxoplasma gondii. Two cis-acting regions within the rps9 transit domain (amino acids 38-49 and 79-86), when combined with the rps9 signal sequence, were necessary and sufficient for apicoplast targeting. To investigate proteins interacting with the rps9 leader sequence, parasites expressing rps9 leader constructs fused to a glutathione S-transferase (GST) reporter were prepared, and proteins associated with the leader constructs were purified from extracts by affinity chromatography. In addition to GST-containing peptides, proteins with apparent masses of 92, 90, 86, and 160 kDa were purified. Mass spectrometry data suggested that the 92- and 90-kDa polypeptides appear to be subtilisin-like proteins, whereas the 86-kDa polypeptide was identified as the molecular chaperone BiP of T. gondii.
authors.affiliation: Division of Geographic Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: Sunny C
authors.initials: SC
authors.lastname: Yung
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Unnasch
authors.forename: Naomi
authors.initials: N
authors.lastname: Lang-Unnasch
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D002846:Chromatography, Affinity; D000091342:Endoplasmic Reticulum Chaperone BiP; D005347:Fibroblasts / Q000469:parasitology; D005656:Fungal Proteins; D005982:Glutathione Transferase / Q000235:genetics / Q000502:physiology; D049452:Green Fluorescent Proteins; D006360:Heat-Shock Proteins; D006801:Humans; D007202:Indicators and Reagents / Q000737:chemistry; D008164:Luminescent Proteins / Q000737:chemistry; D013058:Mass Spectrometry; D018832:Molecular Chaperones / Q000032:analysis / Q000737:chemistry; D008969:Molecular Sequence Data; D015388:Organelles / Q000737:chemistry*; D010449:Peptide Mapping; D021382:Protein Sorting Signals / Q000502:physiology; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000235:genetics; D014122:Toxoplasma / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D014162:Transfection; D014709:Vero Cells / Q000469:parasitology
chemical_list: D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D018832:Molecular Chaperones; D021382:Protein Sorting Signals; D012269:Ribosomal Proteins; C105783:Su12 protein, Podospora anserina; D049452:Green Fluorescent Proteins; D005982:Glutathione Transferase