title: Binding of human BiP to the ER stress transducers IRE1 and PERK requires ATP.
abstract: ER stress is activated in a number of important diseases such as diabetes, cancer, and neurodegeneration, but the molecular interactions governing the response are still being elucidated. In the absence of stress, protein complexes exist between the ER-resident chaperone BiP and three transmembrane signalling molecules which are responsible for signal transmission. Previous results suggested that cofactors might participate in these interactions, but the molecular details are not well understood. We coexpressed BiP and the lumenal domains of each of the three ER stress transducers and copurified the complexes in the presence of ATP and ADP in order to better understand how the complex is formed. ATP, but not ADP, was required to isolate the BiP-IRE1 and the BiP-PERK complexes, but the BiP-ATF6 complex was purified in all conditions tested. Based on the results, we hypothesize that in contrast to its mode of binding ATF6 and unfolded proteins, BiP binds to IRE1 and PERK in a different manner.
authors.affiliation: Centre for Process Systems Engineering, Department of Chemical Engineering and Chemical Technology, Imperial College, London SW7 2AZ, United Kingdom. si.sou07@imperial.ac.uk
authors.forename: Si Nga
authors.initials: SN
authors.lastname: Sou
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Ilieva
authors.forename: Karen M
authors.initials: KM
authors.lastname: Polizzi
mesh_terms: D051702:Activating Transcription Factor 6 / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress; D004722:Endoribonucleases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D051702:Activating Transcription Factor 6; D000255:Adenosine Triphosphate; D000091342:Endoplasmic Reticulum Chaperone BiP; D004722:Endoribonucleases; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D017346:Protein Serine-Threonine Kinases; D011994:Recombinant Proteins; D019892:eIF-2 Kinase; C497111:ATF6 protein, human; C403982:ERN2 protein, human; C460640:EIF2AK3 protein, human