Yolk granule tethering: A role in cell resealing and identification of several protein components

Anna McNeil, Paul L. McNeil

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Homotypic fusion among echinoderm egg yolk granules has previously been reconstituted in vitro, and shown to be a rapid, Ca2+-triggered reaction that can produce extremely large (>10μm diameter) fusion products. We here show that, prior to Ca2+-triggered fusion, yolk granules in vitro, if isolated in an appropriate buffer, became tethered to one another, forming large aggregates of more than 100 granules. Granule washing with mildly chaotropic salt abolished this tethering reaction, and prevented Ca2+-triggered formation of the large fusion products characteristic of tethered granules. Protein factors present in the wash restored tethering activity and these factors could be substantially enriched by anion exchange chromatography. The enriched fraction behaved under native conditions as a high molecular weight (∼670 kDa), multisubunit complex of at least seven proteins. Monoclonal antibodies directed against this complex of proteins were capable of immunodepleting tethering activity, confirming the role of the complex in granule tethering. These antibodies selectively stained the surface of yolk granules in the intact egg. We therefore propose a new role for tethering: it can promote the formation of large vesicular fusion products, such as those required for successful resealing. We have, moreover, identified several proteins that may be critical to this tethering mechanism.

Original languageEnglish (US)
Pages (from-to)4701-4708
Number of pages8
JournalJournal of Cell Science
Volume118
Issue number20
DOIs
StatePublished - Oct 15 2005

Keywords

  • Calcium
  • Fusion
  • Membranes
  • Resealing
  • Tethering

ASJC Scopus subject areas

  • Cell Biology

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