Stereospecific recognition sites for [3H]inositol(1,4,5)-trisphosphate in particulate preparations of rat cerebellum

Inositol 1,4,5‐trisphosphate‐stimulated calcium release from permeabilized cerebellar granule cells

“…However, in agreement with the Ca2 + release data, we observed stereo-specific [32P]-Ins(1,4,5)P3 binding to crude cerebellar granule cell membrane preparations. The cerebellar granule cell Ins(1,4,5)P3 receptor exhibited a similar affinity to that reported for whole cerebellum; however, the receptor density was low (1.37 + 0.29 pmol mg-1 protein), relative to the values (1I30pmol mg'-protein) reported for whole cerebellum (Willcocks et al, 1987;Worley et al, 1987a;, suggesting that the Ins(1,4,5)P3 receptor density of cerebellar granule cells may be masked by that present in Purkinje cells. Furthermore, the possibility should be considered that as a neonatal culture, the presence of these sites may not reflect the mature granule cells, and the distribution of Ins(1,4, 5)P3 binding-sites in neonatal cerebellum would be worthy of further investigation.…”

Muscarinic receptors coupled to phosphoinositide hydrolysis and elevated cytosolic calcium in a human neuroblastoma cell line SK‐N‐SH

“…It is interesting to note that the production of total inositol phosphates ( Figure la) (Strupish et al, 1988) that the mobilization of calcium from intracellular pools is stereospecific, with the D-isomer of Ins(1,4,5) -P3 being active whilst the L-isomer and Ins(1,3,4)P3 were inactive. Indeed D-Ins(1,4,5)P3 had 2000 fold greater affinity than L-InsP3 to receptor sites in cerebellum (Willcocks et al, 1987). Thus, SK-N-SH cells display ATP-dependent high affinity uptake of 45Ca + into non-mitochondrial stores which can be released by D-Ins(1,4,5)P3.…”

Solubilization and separation of inositol 1,3,4,5-tetrakisphosphate- and inositol 1,4,5-trisphosphate-binding proteins and metabolizing enzymes in rat brain

“…One product of the hydrolysis, Ins(1,4,5)P3 (hereafter InsP3) is a modulator of Ca2+ levels within the cell (for reviews see [1,2]). InsP3 releases intracellular Ca2+ after binding to specific intracellular membrane-associated receptors, which have been identified in a wide variety of tissues [3][4][5][6][7][8][9][10][11]. Recently this receptor was purified to homogeneity from brain tissue [12].…”

“…InsP3 kinase and InsP3 phosphatase InsP3 kinase was measured by incubating [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Binding to cytoplasmic or detergent-solubilized fractions was assayed by spun-column chromatography [12]. Separation of enzyme activity NaCl (final concn.…”