A gamete-specific, sex-limited homeodomain protein in Chlamydomonas

Venkatesh Kurvari, Nick V. Grishin, William J. Snell

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

During fertilization in Chlamydomonas, gametes of opposite mating types interact with each other through sex-specific adhesion molecules on their flagellar surfaces. Flagellar adhesion brings the cell bodies of the gametes into close contact and initiates a signal transduction pathway in preparation for cell-cell fusion. We have identified a cDNA, gsp1, whose transcript levels are upregulated during flagellar adhesion. The GSP1 polypeptide is a novel, gamete-specific homeodomain protein, the first to be identified in an alga. Its homeodomain shows significant identity with several higher plant homeodomain proteins. Although encoded by a single copy gene present in cells of both mating types, immunoblot analysis showed that GSP1 was expressed in mating type (mt)+ gametes, but was not detectable in mt- gametes or in vegetative cells of either mating type. Moreover, GSP1 appeared late during gametogenesis, suggesting that it may function during adhesion with mt- gametes or after zygote formation. GSP1 is expressed in imp11, mt- mutant gametes, which have a lesion in the mid gene involved in sex determination and exhibit many phenotypic characteristics of mt+ gametes. Thus, gsp1 is negatively regulated by mid and is the first molecule to be identified in Chlamydomonas that shows sex-limited expression.

Original languageEnglish (US)
Pages (from-to)1971-1980
Number of pages10
JournalJournal of Cell Biology
Volume143
Issue number7
DOIs
StatePublished - Dec 28 1998

Keywords

  • Cell-cell adhesion
  • Chlamydomonas
  • Fertilization
  • Homeodomain
  • Sex-limited

ASJC Scopus subject areas

  • Cell Biology

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