title: ERp44 C160S/C212S mutants regulate IP3R1 channel activity.
abstract: Previous studies have indicated that ERp44 inhibits inositol 1,4,5-trisphosphate (IP(3))-induced Ca(2+) release (IICR) via IP(3)R(1), but the mechanism remains largely unexplored. Using extracellular ATP to induce intracellular calcium transient as an IICR model, Ca(2+) image, pull down assay, and Western blotting experiments were carried out in the present study. We found that extracellular ATP induced calcium transient via IP(3)Rs (IICR) and the IICR were markedly decreased in ERp44 overexpressed Hela cells. The inhibitory effect of C160S/C212S but not C29S/T396A/ΔT(331-377) mutants of ERp44 on IICR were significantly decreased compared with ERp44. However, the binding capacity of ERp44 to L3V domain of IP(3)R(1) (1L3V) was enhanced by ERp44 C160S/C212S mutation. Taken together, these results suggest that the mutants of ERp44, C160/C212, can more tightly bind to IP(3)R(1) but exhibit a weak inhibition of IP(3)R(1) channel activity in Hela cells.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics of Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Congyan
authors.initials: C
authors.lastname: Pan
authors.forename: Ji
authors.initials: J
authors.lastname: Zheng
authors.forename: Yanyun
authors.initials: Y
authors.lastname: Wu
authors.forename: Yingxiao
authors.initials: Y
authors.lastname: Chen
authors.forename: Likun
authors.initials: L
authors.lastname: Wang
authors.forename: Zhansong
authors.initials: Z
authors.lastname: Zhou
authors.forename: Wenxuan
authors.initials: W
authors.lastname: Yin
authors.forename: Guangju
authors.initials: G
authors.lastname: Ji
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D019943:Amino Acid Substitution; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D018613:Microscopy, Confocal; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010957:Plasmids; D014162:Transfection
chemical_list: C451899:ERP44 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008565:Membrane Proteins; D018832:Molecular Chaperones; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002118:Calcium