| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2002: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Inositol 1,4,5-trisphosphate (IP_3) is a second messenger generated by the phosphatidylinositol signaling cascade response to hormones, neurotransmitters, and growth factors and causes Ca^<2+> release from intracellular stores by binding to the IP_3 receptor (IP_3R), which is an IP_3-gated intracellular Ca^<2+> release channel. Ca^<2+> release in the cytoplasm occurs in complex spatial and temporal patterns, such as Ca^<2+> waves and Ca^<2+> oscillations, and regulates many cellular responses, including fertilization, muscle contraction, secretion, cell growth, differentiation, apoptosis, and synaptic plasticity. In this research, we isolated cDNAs encoding type 2 and type 3 IP_3R from mouse lung and found that each type of receptor binds IP_3 with different affinity and cooperativity. We also found that stimulation with ATP of Ca^<2+> ionophore induced cluster formation of all three types of mouse IP_3R expressed in COS-7 cells and that the size and shape of stimulus-induced clusters differ among the three types of IP_3R. The diversity of responsiveness to IP_3 and the intracellular distribution observed among the three IP_3R types may contribute to the generation of the complex spatiotemporal patterns of cytoplasmic Ca^<2+>.
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