| First Author | Nishi T | Year | 2001 |
| Journal | J Biol Chem | Volume | 276 |
| Issue | 36 | Pages | 34122-30 |
| PubMed ID | 11441017 | Mgi Jnum | J:71376 |
| Mgi Id | MGI:2149889 | Doi | 10.1074/jbc.M104682200 |
| Citation | Nishi T, et al. (2001) Expression and localization of the mouse homologue of the yeast V-ATPase 21-kDa Subunit c' (Vma16p). J Biol Chem 276(36):34122-30 |
| abstractText | We have identified a cDNA encoding the mouse homologue of the yeast V-ATPase 21-kDa subunit c' (Vma16p). The encoded protein contains 205 amino acid residues with five putative membrane spanning segments and shows 48% identity and 64% similarity to the yeast protein. Despite this homology, however, the mouse cDNA does not complement the phenotype of a yeast strain in which the VMA16 gene has been disrupted. Northern blot analysis demonstrated that the 21-kDa subunit is expressed in most tissues examined and showed an expression pattern almost identical to that of the 16-kDa proteolipid subunit (subunit c). The presence of multiple mRNA species suggests the existence of alternatively spliced forms of the 21-kDa subunit which, from Southern blot analysis, are derived from a single gene. Promoter analysis using the luciferase reporter gene revealed that a region 186 bases upstream of the initiation site is sufficient to show a low level of transcriptional activity but that transcription is significantly enhanced by inclusion of the region -186 to -706. The 21-kDa protein was Myc-tagged and the 16-kDa protein was HA-tagged and the tagged proteins were co-expressed in COS-1 cells in order to study their intracellular localization by immunofluorescence microscopy. Both proteins showed significant punctate and perinuclear staining and were predominantly co-localized throughout the cell, consistent with their presence in the same V(0) complexes. Selective permeabilization of cells with digitonin (to permeabilize the plasma membrane) or Triton X-100 (to permeabilize both intracellular and plasma membranes) followed by immunofluorescence microscopy revealed that the carboxyl terminus of the 21-kDa subunit is exposed on the cytoplasmic side of the membrane whereas the carboxyl terminus of the 16-kDa subunit is located on the lumenal side of the membrane. |
