title: Extra-renal locations of the a4 subunit of H(+)ATPase.
abstract: Vacuolar-type proton pumps help maintain acid-base homeostasis either within intracellular compartments or at specialised plasma membranes. In mammals they are made up of 13 subunits, which form two functional domains. A number of the subunits have variants that display tissue restricted expression patterns such that in specialised cell types they replace the generic subunits at some sub-cellular locations. The tissue restricted a4 subunit has previously been reported at the plasma membrane in the kidney, inner ear, olfactory epithelium and male reproductive tract.
  
  
  
  In this study novel locations of the a4 subunit were investigated using an Atp6v0a4 knockout mouse line in which a LacZ reporter cassette replaced part of the gene. The presence of a4 in the olfactory epithelium was further investigated and the additional presence of C2 and d2 subunits identified. The a4 subunit was found in the uterus of pregnant animals and a4 was identified along with d2 and C2 in the embryonic visceral yolk sac. In the male reproductive tract a4 was seen in the novel locations of the prostatic alveoli and the ampullary glands as well as the previously reported epididymis and vas deferens.
  
  
  
  The identification of novel locations for the a4 subunit and other tissue-restricted subunits increases the range of unique subunit combinations making up the proton pump. These studies suggest additional roles of the proton pump, indicating a further range of homologue-specific functions for tissue-restricted subunits.
authors.affiliation: Department of Medical Genetics, University of Cambridge, Cambridge, UK.|Cambridge Institute for Medical Research, Cambridge Biomedical Campus Box 139, Hills Road, Cambridge, CB2 OXY, UK.
authors.forename: Zoe J
authors.initials: ZJ
authors.lastname: Golder
authors.affiliation: Department of Medical Genetics, University of Cambridge, Cambridge, UK. fek1000@cam.ac.uk.|Cambridge Institute for Medical Research, Cambridge Biomedical Campus Box 139, Hills Road, Cambridge, CB2 OXY, UK. fek1000@cam.ac.uk.
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Karet Frankl
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D004622:Embryo, Mammalian / Q000378:metabolism; D005260:Female; D005836:Genitalia, Female / Q000378:metabolism; D005837:Genitalia, Male / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D008297:Male; D018345:Mice, Knockout; D008954:Models, Biological; D009831:Olfactory Mucosa / Q000378:metabolism; D009833:Olfactory Pathways / Q000378:metabolism; D009928:Organ Specificity; D021122:Protein Subunits / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases; D019147:Vomeronasal Organ / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D021122:Protein Subunits; D001616:beta-Galactosidase; C490179:Atp6v0a4 protein, mouse; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases
keywords: H+ATPase; Proton pump; Tissue-restricted; Uterus; Yolk sac; a4 subunit