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Gene Review

VMA21  -  Vma21p

Saccharomyces cerevisiae S288c

Synonyms: Vacuolar ATPase assembly integral membrane protein VMA21, YGR105W
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High impact information on VMA21

  • Vma12p and Vma22p migrated to fractions separate from Vma21p [1].
  • In contrast, the proteolipids associate with Vma21p even in the absence of Vma9p [2].
  • We found that in vma21Delta cells, the major proteolipid subunit of V0 failed to interact with the 100-kDa V0 subunit, Vph1p, indicating that Vma21p is necessary for V0 assembly [3].
  • Analysis of vmaDelta strains showed that binding of V0 subunits to Vma21p was mediated by the proteolipid subunit Vma11p [3].
  • An in vitro assay for ER export was used to demonstrate preferential packaging of the fully assembled Vma21p/proteolipid/Vma6p/Vph1p complex into COPII-coated transport vesicles [3].

Biological context of VMA21


Anatomical context of VMA21

  • The product of the VMA21 gene (Vma21p) is an 8.5-kDa integral membrane protein that is not a subunit of the purified V-ATPase complex but instead resides in the endoplasmic reticulum [4].
  • Although a Vma21p mutant lacking an ER-retrieval signal remained associated with V0 in the vacuole, this interaction did not affect the assembly of vacuolar V0/V1 complexes [3].
  • We conclude that Vma21p is not involved in regulating the interaction between V0 and V1 sectors, but that it has a crucial role in coordinating the assembly of V0 subunits and in escorting the assembled V0 complex into ER-derived transport vesicles [3].
  • Immunoprecipitation of Vma21p from wild-type membranes resulted in coimmunoprecipitation of all five V0 subunits [3].
  • The yeast vma21 mutant was isolated from a screen to identify mutants defective in V-ATPase function. vma21 mutants fail to assemble the V-ATPase complex onto the vacuolar membrane: peripheral subunits accumulate in the cytosol and the 100-kDa integral membrane subunit is rapidly degraded [4].

Associations of VMA21 with chemical compounds


Other interactions of VMA21

  • These results indicate that Vma22p, along with Vma21p and Vma12p, form a set of ER proteins required for V-ATPase assembly [5].
  • Unexpectedly, yeast strains lacking Vma21p fail to sort the endoplasmic reticulum to Golgi v-SNARE, Bos1p, efficiently into COPII vesicles, yet these vesicles are fully fusion competent [6].


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