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 electrophoresis followed by the Western blot technique, and by immunofluorescence studies, we have given evidence that calponin is also present in rat and pig brain.

Expression of an acidic isoform of calponin in rat brain: western blots on one- or two-dimensional gels and immunolocalization in cultured cells.

Calponin, an actin- and Ca(2+)-calmodulin-binding protein characterized as an inhibitory factor of the smooth-muscle actomyosin activity, has also been shown to be present in some non-muscle cells. However, there is a controversy as to whether calponin is present or not in brain. Several laboratories indicate that this protein is absent in chicken or bovine brains, while Applegate et al.