TY - JOUR T1 - Ca2+ stores in Purkinje neurons: endoplasmic reticulum subcompartments demonstrated by the heterogeneous distribution of the InsP3 receptor, Ca(2+)-ATPase, and calsequestrin JF - The Journal of Neuroscience JO - J. Neurosci. SP - 489 LP - 505 DO - 10.1523/JNEUROSCI.12-02-00489.1992 VL - 12 IS - 2 AU - K Takei AU - H Stukenbrok AU - A Metcalf AU - GA Mignery AU - TC Sudhof AU - P Volpe AU - P De Camilli Y1 - 1992/02/01 UR - http://www.jneurosci.org/content/12/2/489.abstract N2 - The nature of second messenger-responsive intracellular Ca2+ stores in neurons remains open for discussion. Here, we demonstrate the existence in Purkinje cells (PCs) of endoplastic reticulum (ER) subcompartments characterized by an uneven distribution of three proteins involved in Ca2+ storage and release: the inositol 1,4,5-trisphosphate (InsP3) receptor, Ca(2+)-ATPase, and calsequestrin. Ca(2+)-ATPase and the InsP3 receptor have a widespread, although not identical, distribution throughout the ER. Calsequestrin is localized throughout the smooth ER and is particularly concentrated in pleiomorphic vesicles with a moderately electron-dense core, which appear to represent a subcompartment of the smooth ER. In double-labeling experiments many of these vesicles were unlabeled by InsP3 receptor antibodies. These results suggest a key role of the ER as an intracellular Ca2+ store and demonstrate a possible structural basis for distinct intracellular Ca2+ pools regulated by different second messengers. ER -