The nuclear inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate receptors.
IP3R is located to the inner nuclear membrane. Nuclear IP3R is recognized as a 220 kD immunoreactive protein by antisera raised against purified rat brain IP3R. Antisera against C-terminal 95-108 peptide fragment derived from rat brain IP3R does not reveal immunoreactivity in the nucleus. Nuclear IP3R is sensitive to heparin and is phosphorylated by nuclear PKC, enhancing the efficiency of IP3 in nuclear calcium release. There are two IP4 binding sites located to the nuclear envelope. The nuclear IP4R is sensitive to pH and pH 6.5 is found optimum for the ligand binding. The high affinity IP4R is associated with the outer nuclear membrane and mediates nuclear calcium uptake by IP4. Low affinity IP4R is identified with the inner nuclear membrane and is not involved in IP4 mediated calcium entry into the nucleus. The nature of IP4R associated with the outer nuclear membrane as compared with the one identified with the inner nuclear membrane remains to be elucidated.
Malviya
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Laboratoire de Neurobiologie Moléculaire des Interactions Cellulaires, Centre National de la Recherche Scientifique, Strasbourg, France.
D000818:Animals; D001667:Binding, Competitive; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000032:analysis* / Q000502:physiology; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008099:Liver / Q000648:ultrastructure; D009685:Nuclear Envelope / Q000737:chemistry / Q000648:ultrastructure; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis* / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; C061107:inositol-1,3,4,5-tetrakisphosphate receptor; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium