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Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae
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VMA12 encodes a yeast endoplasmic reticulum protein required for vacuolar H+-ATPase assembly

D D Jackson1, T H Stevens

  • 1Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229, USA.

The Journal of Biological Chemistry
|November 5, 1997
PubMed

Insights

The VMA12 gene product, Vma12p, is crucial for assembling the vacuolar proton-translocating ATPase (V-ATPase) V0 complex in the endoplasmic reticulum. Its absence leads to rapid degradation of the V0 100-kDa subunit, impacting V-ATPase stability and transport.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The vacuolar membrane proton-translocating ATPase (V-ATPase) is essential for cellular function, comprising V1 and V0 complexes.
  • Assembly of the V-ATPase V0 complex requires accessory proteins, including Vma12p, which localizes to the endoplasmic reticulum (ER).

Purpose of the Study:

  • To elucidate the function of Vma12p in the assembly and stability of the V-ATPase V0 complex within the ER.

Main Methods:

  • Genetic analysis of Saccharomyces cerevisiae lacking VMA12 (vma12Δ).
  • Biochemical characterization of Vma12p as an integral ER membrane protein.
  • Protease protection assays to assess V0 subunit insertion and stability.

Main Results:

  • Vma12p is an integral ER membrane protein with cytosolic N and C termini.
  • In vma12Δ cells, the V0 100-kDa subunit is rapidly degraded, despite correct insertion into the ER membrane.
  • Vma12p functions post-insertion, facilitating V0 subunit assembly for stability and ER export.

Conclusions:

  • Vma12p is essential for the proper assembly of V-ATPase V0 subunits in the ER.
  • Assembly mediated by Vma12p is critical for V0 subunit stability and subsequent transport from the ER.

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