A parafusin-related Toxoplasma protein in Ca<sup>2+</sup>-regulated secretory organelles

Steen H. Matthiesen, Shailesh M. Shenoy, Kami Kim, Robert H. Singer, Birgit H. Satir

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

We cloned a gene, PRP1, of Toxoplasma gondii encoding a 637-amino-acids protein having a calculated mass of 70 kDa. The sequence showed high homology to parafusin, a protein that in Paramecium tetraurelia participates in Ca<sup>2+</sup>-regulated exocytosis and is a paralog of phosphoglucomutase. We show that Toxoplasma gondii homogenate and an expressed recombinant PRP1 fusion protein cross-react with a specific peptide-derived antibody to parafusin in Western blots. Antibodies to the recombinant PRP1 showed cross-reaction with parafusin and recognized PRP1, as bands at M<inf>r</inf> 63 × 10<sup>3</sup> and 68 × 10<sup>3</sup>, respectively. PRP1 is labeled when Toxoplasma gondii cells are incubated with inorganic <sup>32</sup>P and appears as the major band on autoradiograms of SDS-PAGE gels. The localization of PRP1 was examined in secretory organelles of Toxoplasma gondii by deconvolution light microscopy followed by three dimensional reconstruction using pairwise combinations of specific antibodies. PRP1 localized to the apical third of the cell. It colocalized with micronemes, the only secretory organelle the secretion of which is Ca<sup>2+</sup> dependent. Quantification of the colocalized stain suggests that only mature micronemes ready for exocytosis have PRP1. These findings suggest that PRP1, parafusin and other members of the phosphoglucomutase superfamily have a conserved role in Ca<sup>2+</sup>-regulated exocytic processes.

Original languageEnglish (US)
Pages (from-to)775-783
Number of pages9
JournalEuropean Journal of Cell Biology
Volume80
Issue number12
StatePublished - 2001

Fingerprint

Toxoplasma
Organelles
Phosphoglucomutase
Exocytosis
Antibodies
Proteins
Paramecium tetraurelia
Recombinant Fusion Proteins
Cross Reactions
Polyacrylamide Gel Electrophoresis
Microscopy
Coloring Agents
Western Blotting
Gels
Light
Amino Acids
Peptides
Genes

Keywords

  • Exocytosis
  • Gondii-3-D deconvolution
  • PGM superfamily
  • PRP1
  • Toxoplasma

ASJC Scopus subject areas

  • Anatomy
  • Cell Biology

Cite this

A parafusin-related Toxoplasma protein in Ca<sup>2+</sup>-regulated secretory organelles. / Matthiesen, Steen H.; Shenoy, Shailesh M.; Kim, Kami; Singer, Robert H.; Satir, Birgit H.

In: European Journal of Cell Biology, Vol. 80, No. 12, 2001, p. 775-783.

Research output: Contribution to journalArticle

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