Simultaneous binding of the N- and C-terminal cytoplasmic domains of aquaporin 4 to calmodulin

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dc.contributor.authorIshida, Hiroaki
dc.contributor.authorVogel, Hans J
dc.contributor.authorConner, Alex C
dc.contributor.authorKitchen, Philip
dc.contributor.authorBill, Roslyn M
dc.contributor.authorMacDonald, Justin A
dc.date.accessioned2022-06-10T16:32:07Z
dc.date.available2022-06-10T16:32:07Z
dc.date.issued2022-01
dc.description.abstractAquaporin 4 (AQP4) is a water transporting, transmembrane channel protein that has important regulatory roles in maintaining cellular water homeostasis. Several other AQP proteins exhibit calmodulin (CaM)-binding properties, and CaM has recently been implicated in the cell surface localization of AQP4. The objective of the present study was to assess the CaM-binding properties of AQP4 in detail. Inspection of AQP4 revealed two putative CaM-binding domains (CBDs) in the cytoplasmic N- and C-terminal regions, respectively. The Ca2+-dependent CaM-binding properties of AQP4 CBD peptides were assessed using fluorescence spectroscopy, isothermal titration calorimetry, and two-dimensional 1H, 15N-HSQC NMR with 15N-labeled CaM. The N-terminal CBD of AQP4 predominantly interacted with the N-lobe of CaM with a 1:1 binding ratio and a Kd of 3.4 μM. The C-terminal AQP4 peptide interacted with both the C- and N-lobes of CaM (2:1 binding ratio; Kd1: 3.6 μM, Kd2: 113.6 μM, respectively). A recombinant AQP4 protein domain (recAQP4CT, containing the entire cytosolic C-terminal sequence) bound CaM in a 1:1 binding mode with a Kd of 6.1 μM. A ternary bridging complex could be generated with the N- and C-lobes of CaM interacting simultaneously with the N- and C-terminal CBD peptides. These data support a unique adapter protein binding mode for CaM with AQP4.en_US
dc.identifier.citationIshida, H., Vogel, H. J., Conner, A. C., Kitchen, P., Bill, R. M., & MacDonald, J. A. (2022). Simultaneous binding of the N-and C-terminal cytoplasmic domains of aquaporin 4 to calmodulin. Biochimica et Biophysica Acta (BBA)-Biomembranes, 1864(2), 183837.en_US
dc.identifier.doihttp://dx.doi.org/10.1016/j.bbamem.2021.183837en_US
dc.identifier.issn0005-2736
dc.identifier.urihttp://hdl.handle.net/1880/114716
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.publisher.departmentBiochemistry & Molecular Biologyen_US
dc.publisher.facultyCumming School of Medicineen_US
dc.publisher.hasversionacceptedVersionen_US
dc.publisher.institutionUniversity of Calgaryen_US
dc.publisher.institutionAston Universityen_US
dc.publisher.institutionUniversity of Birminghamen_US
dc.publisher.policyhttp://www.elsevier.com/about/open-access/green-open-accessen_US
dc.subjectAQP4en_US
dc.subjectCaM
dc.subjectCalmodulin
dc.subjectCalmodulin-binding domain
dc.subjectNMR
dc.subjectNuclear magnetic resonance spectroscopy
dc.subjectAquaporin
dc.titleSimultaneous binding of the N- and C-terminal cytoplasmic domains of aquaporin 4 to calmodulinen_US
dc.typejournal articleen_US
ucalgary.item.requestcopytrueen_US
ucalgary.scholar.levelFaculty, Research Associateen_US
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