Expression of calmin, a novel developmentally regulated brain protein with calponin-homology domains

We examined the expression in the mouse brain of a recently isolated protein named calmin that has two calponin-homology domains in tandem at the N-terminus and a transmembrane domain at the C-terminus. Calmin mRNA and protein were detected in neurons of the hippocampus, cerebral cortex, and thalamus, Purkinje cells, and also in the choroid plexus and ependymal cells. The protein is present predominantly in dendrites and cell bodies of the neurons, but not in axons. Furthermore, the amounts of calmin mRNA and protein increase during the period of maturation of the mouse brain after birth, in a manner similar to that of PSD95 and synaptophysin. These results indicate that calmin may be involved in the development and/or maintenance of neuronal functions.