title: Interaction between Na-K-ATPase and Bcl-2 proteins BclXL and Bak.
abstract: In silico analysis predicts interaction between Na-K-ATPase (NKA) and Bcl-2 protein canonical BH3- and BH1-like motifs, consistent with NKA inhibition by the benzo-phenanthridine alkaloid chelerythrine, a BH3 mimetic, in fetal human lens epithelial cells (FHLCs) (Lauf PK, Heiny J, Meller J, Lepera MA, Koikov L, Alter GM, Brown TL, Adragna NC. Cell Physiol Biochem 31: 257-276, 2013). This report establishes proof of concept: coimmunoprecipitation and immunocolocalization showed unequivocal and direct physical interaction between NKA and Bcl-2 proteins. Specifically, NKA antibodies (ABs) coimmunoprecipitated BclXL (B-cell lymphoma extra large) and BAK (Bcl-2 antagonist killer) proteins in FHLCs and A549 lung cancer cells. In contrast, both anti-Bcl-2 ABs failed to pull down NKA. Notably, the molecular mass of BAK1 proteins pulled down by NKA and BclXL ABs appeared to be some 4-kDa larger than found in input monomers. In silico analysis predicts these higher molecular mass BAK1 proteins as alternative splicing variants, encoding 42 amino acid (aa) larger proteins than the known 211-aa long canonical BAK1 protein. These BAK1 variants may constitute a pool separate from that forming mitochondrial pores by specifically interacting with NKA and BclXL proteins. We propose a NKA-Bcl-2 protein ternary complex supporting our hypothesis for a special sensor role of NKA in Bcl-2 protein control of cell survival and apoptosis.
authors.affiliation: Cell Biophysics Group, Wright State University Boonshoft School of Medicine, Dayton, Ohio; Department of Pathology, Wright State University Boonshoft School of Medicine, Dayton, Ohio; Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio; and peter.lauf@wright.edu.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Lauf
authors.affiliation: Cell Biophysics Group, Wright State University Boonshoft School of Medicine, Dayton, Ohio; Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio; and.
authors.forename: Tariq
authors.initials: T
authors.lastname: Alqahtani
authors.affiliation: Cell Biophysics Group, Wright State University Boonshoft School of Medicine, Dayton, Ohio; Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio; and.
authors.forename: Karin
authors.initials: K
authors.lastname: Flues
authors.affiliation: Environmental Health, University of Cincinnati Medical Center, Cincinnati, Ohio.
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Meller
authors.affiliation: Cell Biophysics Group, Wright State University Boonshoft School of Medicine, Dayton, Ohio; Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, Ohio; and.
authors.forename: Norma C
authors.initials: NC
authors.lastname: Adragna
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D002470:Cell Survival; D003198:Computer Simulation; D030562:Databases, Protein; D004847:Epithelial Cells / Q000201:enzymology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D007908:Lens, Crystalline / Q000166:cytology / Q000201:enzymology*; D008175:Lung Neoplasms / Q000201:enzymology*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism*; D051020:bcl-X Protein / Q000378:metabolism*
chemical_list: C494772:BAK1 protein, human; C494811:BCL2L1 protein, human; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Bcl-2 proteins BclXL and Bak; Na-K-ATPase; cancer cells; human lens epithelial cells; immunochemistry