Subcellular distribution of calponin and caldesmon in rat hippocampus

Caldesmon and calponin are two actin- and calmodulin-binding proteins involved in the 'actin-linked' regulation of smooth muscle and non-muscle Mg2+-actin-activated myosin II ATPase activity. In the present report we show that caldesmon and calponin are present in the post-synaptic side of symmetric synapses and accumulate in the post-synaptic densities of asymmetric synapses. Caldesmon- and calponin-immunoreactivities are also observed at the plasma membrane of the hippocampal neurones. Finally, while caldesmon seems strictly distributed to neurones, acidic calponin is present in both neurones and astrocytes. (C) 2000 Elsevier Science B.V. All rights reserved.