title: The phosphorylation status of membrane-bound nucleoside diphosphate kinase in epithelia and the role of AMP.
abstract: Nucleoside diphosphate kinase (NDPK) has many roles and is present in different locations in the cell. Membrane-bound NDPK is present in epithelial fractions enriched for the apical membrane. Here, we show in human, mouse and sheep airway membranes, that the phosphorylation state of membrane-bound NDPK on histidine and serine residues differs dependent on many regulatory factors. GTP (but not ATP) promotes serine phosphorylation (pSer) of NDPK. Further we find that rising [AMP] promotes pSer (only with GTP) but inhibits histidine phosphorylation (pHis) of NDPK from both donors. We find that NDPK co-immunoprecipitates reciprocally with AMP-activated kinase and that these two proteins can co-localise in human airways. AMP concentrations rise rapidly when ATP is depleted or during hypoxia. We find that, in human airway cells exposed to hypoxia (3% oxygen), membrane-bound NDPK is inhibited. Although histidine phosphorylation should in principle be independent of the nucleotide triphosphates used, we speculate that this membrane pool of NDPK may be able to switch function dependent on nucleotide species.
authors.affiliation: Division of Medical Sciences, Ninewells Hospital and Medical School, University of Dundee, Dundee DD19SY, UK.
authors.forename: Kate J
authors.initials: KJ
authors.lastname: Treharne
authors.forename: Oliver Giles
authors.initials: OG
authors.lastname: Best
authors.forename: Anil
authors.initials: A
authors.lastname: Mehta
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001980:Bronchi / Q000166:cytology; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D006157:Guanosine Monophosphate / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008970:Molecular Weight; D009701:Nucleoside-Diphosphate Kinase / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D012756:Sheep; D014132:Trachea / Q000201:enzymology / Q000378:metabolism; D014542:Uridine Monophosphate / Q000494:pharmacology
chemical_list: D008565:Membrane Proteins; D000249:Adenosine Monophosphate; D006157:Guanosine Monophosphate; D014542:Uridine Monophosphate; D055372:AMP-Activated Protein Kinases; D009701:Nucleoside-Diphosphate Kinase