Molecular cloning of mouse type 2 and type 3 inositol 1,4,5-trisphosphate receptors and identification of a novel type 2 receptor splice variant
Molecular cloning of mouse type 2 and type 3 inositol 1,4,5-trisphosphate receptors and identification of a novel type 2 receptor splice variant
复制标题
DOI：
10.1074/jbc.m413824200
复制
发表时间：
2005-03-18
影响因子：
4.8
通讯作者：
Mikoshiba, K
中科院分区：
文献类型：
--
作者：
Iwai, M;Tateishi, Y;Mikoshiba, K
我们从小鼠肺中分离了编码2型和3型肌醇1,4,5-三磷酸（IP3）受体（分别为IP(3)R2和IP(3)R3）的cDNA，并在IP3R2的176-208处发现了一个新的替代剪接片段SIm2。长形式 (IP(3)R2 SIm2+) 占主导地位，但在所有检查的组织中均检测到短形式 (IP(3)R2 SIm2-)。 IP(3)R2 SIm2-既不具有IP3结合活性，也不具有Ca2+释放活性。除了其网状分布外，IP(3)R2 SIm2+ 以簇的形式存在于静息 COS-7 细胞的内质网中，并且在 ATP 或 Ca2+ 离子载体刺激后，大部分 IP(3)R2 SIm2+ 呈簇状。 IP(3)R3 均匀定位于静息细胞的内质网上，并在 ATP 或 Ca2+ 离子载体刺激后形成簇。 IP(3)R2 SIm2- 在静息或受刺激的细胞中均不形成簇。 IP(3)R2 SIm2+ 和 IP(3)R3 的 IP3 结合缺陷定点突变体无法形成簇，表明 IP3 结合参与了这些亚型的簇形成。 IP(3)R2 SIm2+ 的共表达可防止刺激诱导的 IP3R 聚类，表明 IP(3)R2 SIm2- 充当刺激诱导的 IP3R 聚类的负协调子。 CHO-K1 细胞中 IP(3)R2 SIm2- 的表达显着减少 ATP 诱导的 Ca2+ 进入，但不会减少 Ca2+ 释放，表明 IP(3)R2 的新型剪接变体特异性影响 Ca2+ 信号持续相的动态。
We isolated cDNAs encoding type 2 and type 3 inositol 1,4,5-trisphosphate (IP3) receptors (IP(3)R2 and IP(3)R3, respectively) from mouse lung and found a novel alternative splicing segment, SIm2, at 176-208 of IP3R2. The long form (IP(3)R2 SIm2+) was dominant, but the short form (IP(3)R2 SIm2-) was detected in all tissues examined. IP(3)R2 SIm2- has neither IP3 binding activity nor Ca2+ releasing activity. In addition to its reticular distribution, IP(3)R2 SIm2+ is present in the form of clusters in the endoplasmic reticulum of resting COS-7 cells, and after ATP or Ca2+ ionophore stimulation, most of the IP(3)R2 SIm2+ is in clusters. IP(3)R3 is localized uniformly on the endoplasmic reticulum of resting cells and forms clusters after ATP or Ca2+ ionophore stimulation. IP(3)R2 SIm2- does not form clusters in either resting or stimulated cells. IP3 binding-deficient site-directed mutants of IP(3)R2 SIm2+ and IP(3)R3 fail to form clusters, indicating that IP3 binding is involved in the cluster formation by these isoforms. Coexpression of IP(3)R2 SIm2+ prevents stimulus-induced IP3R clustering, suggesting that IP(3)R2 SIm2- functions as a negative coordinator of stimulus-induced IP3R clustering. Expression of IP(3)R2 SIm2- in CHO-K1 cells significantly reduced ATP-induced Ca2+ entry, but not Ca2+ release, suggesting that the novel splice variant of IP(3)R2 specifically influences the dynamics of the sustained phase of Ca2+ signals.