The plasma membrane Ca(2+)-ATPase mRNA isoform PMCA 4 is expressed at high levels in neurons of rat piriform cortex and neocortex.

Ca2+ transport mediated by the plasma membrane Ca(2+)-ATPase (PMCA) serves an important role in regulation of cytosolic-free Ca2+ in a variety of cells. Isoform PMCA4 mRNA distribution in rat brain was studied by in situ hybridization using 33P-labeled antisense oligodeoxynucleotide probes. Very high levels of hybridization were found in piriform cortex with high levels in amygdaloid nucleus and laminae 2 and 6 of cerebral cortex. Significantly lower levels were found in hypothalamic nuclei and very low or undetectable levels were found in cerebellum, habenula, olfactory bulb, thalamus, choroid plexus of the third and fourth ventricles and in CA1 and CA3 cells of the hippocampus. These results suggest that PMCA4 is not a housekeeping form of the Ca(2+)-ATPase.