Volpe P, Alderson-Lang B H, Madeddu L, Damiani E, Collins J H, Margreth A
Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77550.
Neuron. 1990 Nov;5(5):713-21. doi: 10.1016/0896-6273(90)90225-5.
The presence and distribution of calsequestrin (CS), Ca2+ pump, and inositol 1,4,5-trisphosphate (IP3) receptor were investigated biochemically and immunologically in microsomal (P3) fractions isolated from chicken cerebrum and cerebellum. Two different batches of polyclonal antibodies specific for chicken skeletal muscle CS identified a Ca2+ binding, CS-like protein that was extremely enriched in cerebellum P3 fractions and absent from all cerebrum fractions. The cerebellum CS-like protein was deemed authentic CS because the N-terminal amino acid domain and peptide mapping were identical to those of skeletal muscle CS in the same species. CS was detected in striated muscles and cerebellum only. Cerebellum P3 fractions were also found to be considerably enriched in Ca2+ pump and IP3 receptor compared with the homologous cerebrum fractions, as judged by measurements of Ca2+ uptake, Ca2(+)-ATPase activity, IP3-induced Ca2+ release, and [3H]IP3 binding, respectively. Cerebellum microsomal fractions therefore appear to contain membrane fragments endowed with Ca2+ pump, IP3 receptor, and CS, i.e., three key components of a Ca2+ storage organelle.
运用生化和免疫方法，对从鸡大脑和小脑中分离出的微粒体（P3）组分中的钙结合蛋白（CS）、钙离子泵以及肌醇1,4,5-三磷酸（IP3）受体的存在情况和分布进行了研究。两批针对鸡骨骼肌CS的不同多克隆抗体识别出一种结合钙离子的、类似CS的蛋白，该蛋白在小脑P3组分中高度富集，而在所有大脑组分中均不存在。小脑类似CS的蛋白被认为是真正的CS，因为其N端氨基酸结构域和肽图谱与同一物种的骨骼肌CS相同。仅在横纹肌和小脑中检测到了CS。通过分别测量钙离子摄取、Ca2(+)-ATP酶活性、IP3诱导的钙离子释放以及[3H]IP3结合发现，与同源大脑组分相比，小脑P3组分中的钙离子泵和IP3受体也显著富集。因此，小脑微粒体组分似乎含有具有钙离子泵、IP3受体和CS的膜片段，即钙离子储存细胞器的三个关键组分。
