CaMKII, calcium/calmodulin dependent protein kinase, is an active kinase in the cell that phosphorylates a number of substrates including several cytoskeletal and signaling proteins. In addition to kinase activity, the ÃŸ isoform of CaMKII also contains an F-actin binding region. We recently identified a new F-actin rich structure in developing cortical neurons that endogenous CaMKIIÃŸ bound. In nonneuronal cells and dendrite spines of hippocampal neurons where an interaction between CaMKIIÃŸ and F-actin has been identified, CaMKIIÃŸ was involved in regulating the differentiation of dendrite spines and formation of synapses. In this study, we took advantage of the temporal and spatial regulation of CaMKII isoforms to reveal a specific role for CaMKIIÃŸ in binding and stability of a novel F-actin rich structure. We used FRAP and colocalization assays in this CaMKJIÃŸ rich system to demonstrate a structural, rather than enzymatic, role of CaMKIIÃŸ. In this addendum, we further discuss the significance of this study and the possible implication to the field. Â©2009 Landes Bioscience.
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