The human type 1 inositol 1,4,5-trisphosphate receptor from T lymphocytes. Structure, localization, and tyrosine phosphorylation.
Inositol 1,4,5-trisphosphate receptors (IP3R) are intracellular calcium release channels involved in diverse signaling pathways. An IP3R is thought to play a role in mobilizing calcium required for activation of T lymphocytes. The IP3R is a tetrameric structure comprised of four approximately 300-kDa subunits encoded by a approximately 10-kilobase mRNA. In the present study we determined the structure of the human type 1 IP3R expressed in T lymphocytes (Jurkats). The IP3R in human T cells had a predicted molecular mass of 308 kDa and was most similar to the non-neuronal form of the rodent type 1 IP3R. Two putative tyrosine phosphorylation sites were identified, one near the amino terminus and one near the putative channel pore at the carboxyl terminus. During T cell activation the IP3R was tyrosine phosphorylated. A site-specific anti-IP3R antibody was used to localize the carboxyl terminus of the IP3R to the cytoplasm in T cells.
Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029.
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Harnick
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Jayaraman
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Mulieri
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D000595:Amino Acid Sequence; D015220:Calcium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008969:Molecular Sequence Data; D010766:Phosphorylation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D014443:Tyrosine; D015544:Inositol 1,4,5-Trisphosphate