Two fission yeast Rab7 homologs, Ypt7 and Ypt71, play antagonistic roles in the regulation of vacuolar morphology

Jun Kashiwazaki, Tomoko Iwaki, Kaoru Takegawa, Chikashi Shimoda, Taro Nakamura

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Small guanine triphosphatases (GTPases) of the Rab family are key regulators of membrane trafficking events between the various subcellular compartments in eukaryotic cells. Rab7 is a conserved protein required in the late endocytic pathway and in lysosome biogenesis. A Schizosaccharomyces pombe (S. pombe) homolog of Rab7, Ypt7, is necessary for trafficking from the endosome to the vacuole and for homotypic vacuole fusion. Here, we identified and characterized a second fission yeast Rab7 homolog, Ypt71. Ypt71 is localized to the vacuolar membrane. Cells deleted for ypt71+ exhibit normal growth rates and morphology. Interestingly, a ypt71 null mutant contains large vacuoles in contrast with the small fragmented vacuoles found in the ypt7 null mutant. Furthermore, the ypt71 mutation does not enhance or alleviate the temperature sensitivity or vacuole fusion defect of ypt7 Δ cells. Like ypt7 Δ cells, overexpression of ypt71+ caused fragmentation of vacuoles and inhibits vacuole fusion under hypotonic conditions. Thus, the two S. pombe Rab7 homologs act antagonistically in regulating vacuolar morphology. Analysis of a chimeric Ypt7/Ypt71 protein showed that Rab7-directed vacuole dynamics, fusion versus fission, largely depends on the medial region of the protein, including a part of RabSF3/α3-L7.

Original languageEnglish
Pages (from-to)912-924
Number of pages13
Issue number7
Publication statusPublished - 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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