title: A single PDZ domain protein interacts with the Menkes copper ATPase, ATP7A. A new protein implicated in copper homeostasis.
abstract: The homeostatic regulation of essential elements such as copper requires many proteins whose activities are often mediated and tightly coordinated through protein-protein interactions. This regulation ensures that cells receive enough copper without intracellular concentrations reaching toxic levels. To date, only a small number of proteins implicated in copper homeostasis have been identified, and little is known of the protein-protein interactions required for this process. To identify other proteins important for copper homeostasis, while also elucidating the protein-protein interactions that are integral to the process, we have utilized a known copper protein, the copper ATPase ATP7A, as a bait in a yeast two-hybrid screen of a human cDNA library to search for interacting partners. One of the ATP7A-interacting proteins identified is a novel protein with a single PDZ domain. This protein was recently identified to interact with the plasma membrane calcium ATPase b-splice variants. We propose a change in name for this protein from PISP (plasma membrane calcium ATPase-interacting single-PDZ protein) to AIPP1 (ATPase-interacting PDZ protein) and suggest that it represents the protein that interacts with the class I PDZ binding motif identified at the ATP7A C terminus. The interaction in mammalian cells was confirmed and an additional splice variant of AIPP1 was identified. This study represents an essential step forward in identifying the proteins and elucidating the network of protein-protein interactions involved in maintaining copper homeostasis and validates the use of the yeast two-hybrid approach for this purpose.
authors.affiliation: Centre for Cellular and Molecular Biology, School of Biological and Chemical Sciences, Deakin University, Burwood, Victoria 3125, Australia.
authors.forename: Sarah E M
authors.initials: SE
authors.lastname: Stephenson
authors.forename: Daphne
authors.initials: D
authors.lastname: Dubach
authors.forename: Chris M
authors.initials: CM
authors.lastname: Lim
authors.forename: Julian F B
authors.initials: JF
authors.lastname: Mercer
authors.forename: Sharon
authors.initials: S
authors.lastname: La Fontaine
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D003300:Copper / Q000378:metabolism*; D000073840:Copper-Transporting ATPases; D005347:Fibroblasts / Q000378:metabolism; D015723:Gene Library; D014644:Genetic Variation; D006706:Homeostasis; D006801:Humans; D007706:Menkes Kinky Hair Syndrome / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D027682:Cation Transport Proteins; C505673:PDZD11 protein, human; D011506:Proteins; D011993:Recombinant Fusion Proteins; D003300:Copper; D001616:beta-Galactosidase; D000251:Adenosine Triphosphatases; C081184:ATP7A protein, human; D000073840:Copper-Transporting ATPases