Proteomic analysis of a developmentally regulated secretory vesicle

Supriya Srinivasan, Mathew Traini, Ben Herbert, Diane Sexton, Jenny Harry, Hannah Alexander, Keith L. Williams, Stephen Alexander*

*Corresponding author for this work

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Secretion of spore coat proteins from the prespore secretory vesicles (PSVs) in Dictyostelium discoideum is a signal mediated event that underlies terminal cell differentiation, and represents an important case of developmentally regulated secretion. In order to study the biochemical mechanisms that govern the regulated fusion of the PSVs with the plasma membrane and the subsequent secretion of their cargo, we purified this organelle from prespore cells. Analysis of protein extracts of highly purified PSVs indicated that, in addition to the cargo of structural spore coat proteins, many more proteins are associated with the PSVs. Their identification is paramount to the understanding of the mechanism of regulated secretion in this system. In this study we have taken the first comprehensive proteomic approach to the analysis of an entire, previously uncharacterized, organelle, with the goal of identifying the major proteins associated with the PSVs. We show that in addition to the structural spore coat proteins, the PSVs contain the enzymes needed for proper spore coat assembly (thioredoxin 2 and 3), regulatory proteins which we predict receive and transduce the developmental signal for secretion (rab7 GTPase, PI-3 kinase, NDP kinase and the calcium binding proteins calfumirin-1 and calreticulin) as well as proteins that interact with the cytoskeleton to mediate movement of the PSVs to the plasma membrane (actin binding proteins coactosin and profilin 1). In addition, the results suggest that proteins can play multiple roles in the cell, and that protein function can be dictated in part by subcellular localization. The identification of the PSV proteins is allowing us to develop testable hypotheses about the roles of these proteins within the functional context of developmentally regulated secretion.

Original languageEnglish
Pages (from-to)1119-1127
Number of pages9
JournalProteomics
Volume1
Issue number9
DOIs
Publication statusPublished - Sep 2001

Keywords

  • Actin binding protein
  • Calcium binding protein
  • Dictyostelium
  • NDP kinase
  • Organelle
  • Prespore vesicle
  • Protein secretion
  • Rab GTPase

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