Disease relevance of VMA4

• A recombinant form of subunit E (Vma4p) from yeast vacuolar ATPases (V-ATPases) has been overexpressed in Escherichia coli, purified to homogeneity, and explored by mass spectrometry [1].

High impact information on VMA4

• The ATP hydrolysis rate was 72% of the wild-type rate; but there was no proton translocation, and two V(1) subunits (Vma4p and Vma8p) were present at lower levels [2].
• The Rim101p-dependent gene VMA4 is required for growth in alkaline conditions, illustrating how Rim101p may control adaptation [3].
• Cells lacking a functional VMA4 gene are unable to grow at pH > 7 or in elevated concentrations of CaCl2 [4].
• Plasmid-borne, mutagenized vma4 genes were screened for failure to complement these phenotypes [4].
• Furthermore, we show that the in vivo stability of Vma4p is dependent upon interaction with Vma10p [5].

Biological context of VMA4

• Null vma4 haploid mutants are viable [6].

Anatomical context of VMA4

• The VMA4 gene encodes a 26.6-kDa hydrophilic polypeptide which exhibits 34% sequence identity with the E subunit of the vacuolar ATPase from bovine kidney microsomes [6].

Associations of VMA4 with chemical compounds

• Cells of the delta vma4 mutant strain, with no functional vacuolar H(+)-ATPase, had elevated levels of [Ca2+]i, reaching 1.8 microM when pre-incubated with glucose and exposed to 10 mM CaCl2 [7].

Physical interactions of VMA4

• Yeast two-hybrid data indicate that Vma1p and Vma2p interact with each other and that Vma4p interacts with itself [8].

Other interactions of VMA4

• We report here the characterization of two genes, VMA4 and VMA5, that encode peripheral subunits of the vacuolar H(+)-ATPase [9].
• The chromosomal VMA4 gene was inactivated by a 171-base pair deletion followed by insertion of the URA3 gene within the coding sequence [6].
• The tightly linked VMA4 and MIP1 (encoding the mitochondrial DNA polymerase) genes are divergently transcribed from face-to-face promoters [6].

Analytical, diagnostic and therapeutic context of VMA4

• Analysis of the secondary structure of Vma4p by circular dichroism spectroscopy indicated 32% alpha-helix and 23% beta-sheet content [1].

References