DISTRIBUTION OF CALDESMON AND OF THE ACIDIC ISOFORM OF CALPONIN IN CULTURED CEREBELLAR NEURONS AND IN DIFFERENT REGIONS OF THE RAT-BRAIN - AN IMMUNOFLUORESCENCE AND CONFOCAL MICROSCOPY STUDY

Caldesmon and calponin are two F-actin-binding and calcium-calmodulin- dependent proteins. In smooth muscle and nonmuscle cells both proteins are localized on actin filaments, Using one- or two-dimensional gel e lectrophoresis followed by the Western blot technique, and by immunofl uorescence studies, we have given evidence that calponin is also prese nt in rat and pig brain, In the present study, for the first time, we demonstrate caldesmon- and calponin-specific immunoreactivities in cer ebellar cultured neurons, In the rat central nervous system these anti bodies mainly stain neuronal cell bodies and dendrites, By confocal an alysis we observed that calponin and caldesmon are located in the acto myosin domain although the total actin and myosin were not saturated, In many cases it is clear that these two proteins are adjacent rather than superimposed in the same domain of the cell, These results are co mpatible with the functional role of caldesmon and calponin in the reg ulation of the actomyosin activity as described by others and suggest that they are part of the contractile apparatus of neural cells. (C) 1 995 Academic Press, Inc.