抄録
IP3 receptor (IP3R) is a Ca2+ channel localized on smooth endoplasmic reticulum and is involved in Ca2+ signaling and it plays essential role in development and brain function. We have already found by using IP3R type 1 (IP3R1) deficient mice that IP3R1 is essential for brain development and neural plasticity and other various cell functions. To understand fully the property of IP3R, it is extremely necessary to characterize the biochemical property of IP3R. We purified IP3R1 from the cerebellum and found that the dynamic conformation change occurs in the presence and absence of Ca2+. When it is trypsized into several pieces, they assemble together to function as intact IP3 induced Ca2+ release machinery. These unique biochemical properties may be related in producing Ca2+ wave and oscillation. Recently, we succeeded in screening and cloning many molecules which associate with IP3R1. 4.1N which binds to C-Terminus of IP3R1 is found to be important for translocation of IP3R1 to plasma membrane.IRBIT (IP3 receptor binding protein released with inositol 1,4,5-trisphosphate) binds to the IP3 binding core of IP3R in a phosphorylated form and is released with IP3. IRBIT may regulate IP3 induced Ca2+ release and may work as a third messenger. In addition, new molecules that regulate Ca2+ signaling will be discussed. [Jpn J Physiol 54 Suppl:S38 (2004)]
