title: An isoform of the vacuolar (H(+))-ATPase accessory subunit Ac45.
abstract: The vacuolar (H(+))-ATPase (V-ATPase) is the main regulator of intraorganellar pH and in neuroendocrine cells is controlled by its accessory subunit, Ac45. Here, we report the discovery of the first isoform of a V-ATPase accessory subunit, namely an Ac45-like protein, denoted Ac45LP. Phylogenetic analysis revealed a lineage-dependent evolutionary history: Ac45 is absent in birds, and Ac45LP is absent in placental mammals, whereas all other tetrapod species contain both genes. In contrast to Ac45, Ac45LP is not proteolytically cleaved, a prerequisite for proper Ac45 routing. Intriguingly, Xenopus Ac45LP mRNA was expressed in developing neural tissue and in neural crest cells. In adult Xenopus, Ac45 mRNA is widely expressed mostly in neuroendocrine tissues, while Ac45LP mRNA expression was found to be restricted to the kidney and the lung. This novel Ac45LP may provide additional possibilities for V-ATPase regulation during neurodevelopment as well as in kidney and lung cells.
authors: Donders Institute for Brain, Cognition and Behaviour, and Nijmegen Centre for Molecular Life Sciences (NCMLS), Department of Molecular Animal Physiology, Radboud University Nijmegen, Geert Grooteplein Zuid 28, 6525 GA Nijmegen, The Netherlands.
authors: Eric J R
authors: EJ
authors: Jansen
authors: Nick H M
authors: NH
authors: van Bakel
authors: Anthon J M
authors: AJ
authors: Coenen
authors: Sander H
authors: SH
authors: van Dooren
authors: Hermina A M
authors: HA
authors: van Lith
authors: Gerard J M
authors: GJ
authors: Martens
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D007527:Isoenzymes / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D021122:Protein Subunits; D014018:Tissue Distribution; D025262:Vacuolar Proton-Translocating ATPases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D021122:Protein Subunits; D029867:Xenopus Proteins; C484227:atp6ap1.1 protein, Xenopus; D025262:Vacuolar Proton-Translocating ATPases