title: A role for Na+,K+-ATPase α1 in regulating Rab27a localisation on melanosomes.
abstract: The mechanism(s) by which Rab GTPases are specifically recruited to distinct intracellular membranes remains elusive. Here we used Rab27a localisation onto melanosomes as a model to investigate Rab targeting. We identified the α1 subunit of Na+,K+-ATPase (ATP1a1) as a novel Rab27a interacting protein in melanocytes and showed that this interaction is direct with the intracellular M4M5 loop of ATP1a1 and independent of nucleotide bound status of the Rab. Knockdown studies in melanocytes revealed that ATP1a1 plays an essential role in Rab27a-dependent melanosome transport. Specifically, expression of ATP1a1, like the Rab27a GDP/GTP exchange factor (Rab3GEP), is essential for targeting and activation of Rab27a to melanosomes. Finally, we showed that the ability of Rab27a mutants to target to melanosomes correlates with the efficiency of their interaction with ATP1a1. Altogether these studies point to a new role for ATP1a1 as a regulator of Rab27a targeting and activation.
authors: Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom.
authors: Antonia E G
authors: AE
authors: Booth
authors: Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom.
authors: Abul K
authors: AK
authors: Tarafder
authors: Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom; School of Biomedical Sciences, University of Nottingham, Medical School, Queens Medical Centre, Nottingham, United Kingdom.
authors: Alistair N
authors: AN
authors: Hume
authors: Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom.
authors: Chiara
authors: C
authors: Recchi
authors: Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom; CEDOC, Faculdade de Ciencias Medicas, FCM, Universidade Nova de Lisboa, Lisboa, Portugal.
authors: Miguel C
authors: MC
authors: Seabra
mesh_terms: D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D006801:Humans; D015151:Immunoblotting; D008544:Melanocytes / Q000378:metabolism*; D020460:Melanosomes / Q000378:metabolism*; D051379:Mice; D018613:Microscopy, Confocal; D009154:Mutation; D011485:Protein Binding; D034622:RNA Interference; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000075745:rab27 GTP-Binding Proteins
chemical_list: D011993:Recombinant Fusion Proteins; D000075745:rab27 GTP-Binding Proteins; C499076:ATP1A1 protein, human; C512961:Rab27a protein, rat; D020691:rab GTP-Binding Proteins; D000254:Sodium-Potassium-Exchanging ATPase