A new inositol 1,4,5-trisphosphate binding protein similar to phospholipase C-δ1

Takashi Kanematsu, Yoshio Misumi, Yutaka Watanabe, Shoichiro Ozaki, Toshitaka Koga, Sadaaki Iwanaga, Yukio Ikehara, Masato Hirata

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90 Citations (Scopus)


We have reported that two inositol 1,4,5-trisphosphate binding proteins, with molecular masses of 85 and 130 kDa, were purified from rat brain; the former protein was found to be the δ1-isoenzyme of phospholipase C (PLC-δ1) and the latter was an unidentified novel protein [Kanematsu, Takeya, Watanabe, Ozaki, Yoshida, Koga, Iwanaga and Hirata (1992) J. Biol. Chem. 267, 6518-6525]. Here we describe the isolation of the full-length cDNA for the 130 kDa Ins(1,4,5)P3 binding protein, which encodes 1096 amino acids. The predicted sequence of the 130 kDa protein had 38.2% homology to that of PLC-δ1. Three known domains of PLC-δ1 (pleckstrin homology and putative catalytic X and Y domains) were located at residues 110-222, 377-544 and 585-804 with 35.2%, 48.2% and 45.8% homologies respectively. However, the protein showed no PLC activity to phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol. The 130 kDa protein expressed by transfection in COS-1 cells bound Ins(1,4,5)P3 in the same way as the molecule purified from brain. Thus the 130 kDa protein is a novel Ins(1,4,5)P3 binding protein homologous to PLC-δ1, but with no catalytic activity. The functional significance of the 130 kDa protein is discussed.

Original languageEnglish
Pages (from-to)319-325
Number of pages7
JournalBiochemical Journal
Issue number1
Publication statusPublished - Jan 1 1996

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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