background:
The subunit of the vacuolar proton pump is a SLVATPase that has two different isoforms. The type I isoform contains an 18-base pair insert and is expressed in brain, whereas the truncated type II isoform is more widely expressed, including lung, kidney and spleen. The subunit of the vacuolar proton pump is located in clathrin-coated vesicles and is also found in osteoclasts. It consists of two fundamental domains, a hydrophilic amino-terminus, which has greater than 30% charged residues, and a hydrophobic carboxy terminus, which contains at least six transmembrane regions. The proton pump functions in coupling ATP hydrolysis by the cytoplasmic subunits to proton translocation by the intramembranous components of the pump. The inactivation of the osteoclast-specific vacuolar proton ATPase subunit is responsible for the lack of the enzyme in the apical membranes of osteoclast cells in osteosclerotic mutant mice, thus preventing the resorption function of these cells and leading to the osteopetrotic phenotype. The subunit, which co-localizes with the late endosomal marker Rab7 on vacuolar membranes, is essential for vacuole formation by selective swelling of late endosomes.
Function:
Required for assembly and activity of the vacuolar ATPase. Potential role in differential targeting and regulation of the enzyme for a specific organelle (By similarity).
Subunit:
The SLVATPase is a heteromultimeric enzyme composed of at least thirteen different subunits. It has a membrane peripheral V1 sector for ATP hydrolysis and an integral V0 for proton translocation. The V1 sector comprises subunits A-H, whereas V0 includes subunits a, d, c, c', and c''.
Subcellular Location:
Cytoplasmic vesicle membrane; Multi-pass membrane protein. Melanosome. Note=Coated vesicle. Identified by mass spectrometry in melanosome fractions from stage I to stage IV.
Similarity:
Belongs to the SLVATPase 116 kDa subunit family.
Database links:
Entrez Gene: 395474 Chicken
Entrez Gene: 286768 Cow
Entrez Gene: 535 Human
Entrez Gene: 11975 Mouse
Entrez Gene: 29757 Rat
Omim: 192130 Human
SwissProt: Q9I8D0 Chicken
SwissProt: Q29466 Cow
SwissProt: Q93050 Human
SwissProt: Q9Z1G4 Mouse
SwissProt: P25286 Rat
Unigene: 463074 Human
Unigene: 340818 Mouse
Unigene: 475829 Mouse
Unigene: 6015 Rat
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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