INOSITOL 1,4,5-TRISPHOSPHATE 3-KINASE HIGHEST LEVELS IN THE DENDRITICSPINES OF CEREBELLAR PURKINJE-CELLS AND HIPPOCAMPAL CA1 PYRAMIDAL CELLS - A PREEMBEDDING AND POSTEMBEDDING IMMUNOELECTRON MICROSCOPIC STUDY

Inositol 1,4,5-trisphosphate 3-kinase (InsP3 3-kinase) plays a crucial role in calcium homeostasis by regulating InsP3 levels. We have repor ted the highest concentrations of InsP3 3-kinase in the dendrites of c erebellar Purkinje cells and hippocampal pyramidal cells of the CAl se ctor of the Ammon's horn. We here investigate its subcellular localiza tion by pre- and post-embedding immunoelectron microscopic study. In b oth populations of neurons, the major structure expressing a high leve l of InsP3 3-kinase is the dendritic spines.