Distribution of PCP4 protein in the forebrain of adult mice.

Purkinje-cell protein 4 (PCP4) is a small calmodulin (CaM)-binding protein that has been discovered to be selectively expressed by cerebellar Purkinje cells in the adult rodent brain. In addition, expression of PCP4 mRNA has been detected in the hippocampus and in the cortex. In order to determine the expression of PCP4 protein in the brain, we performed an immunohistochemical analysis using adult mice. We could demonstrate that PCP4 is expressed in neocortical structures, especially in the deep layers, as well as in other cortical structures and parts of the hippocampal formation. Moreover, PCP4 protein is highly expressed in the olfactory bulb and caudate putamen. PCP4 positive cells were also detected in specific areas of the amygdala, thalamus (especially dorsal lateral geniculate nucleus) and hypothalamus. By performing double-labeling experiments together with NeuN (a neuronal marker), we could demonstrate that PCP4 expressing cells in the brain are of neuronal origin.