Ca2þ/calmodulin-dependent protein kinase (CaMK) IV is a multifunctional Ser/Thr protein kinase that is predominantly expressed in the nuclei of neurons. CaMKIV consists of a catalytic domain and a regula-tory (Ca2þ/calmodulin binding and autoinhibitory) domain, which are located in the N-terminal and cen-tral regions, respectively. Here, we identified the zebra-fish homologue of CaMKIV (zCaMKIV) on the basis of biochemical characterization. zCaMKIV showed similar biochemical properties as well as tissue and subcellular distributions to rat CaMKIV (rCaMKIV). However, zCaMKIV had a fairly small size with a mo-lecular mass of about 40 kDa, and was devoid of a region corresponding to the C-terminal domain of rCaMKIV. Since zCaMKIV is composed of regions that are nearly equivalent to only a catalytic and a regulatory domain, it should represent a minimum size homologue possessing CaMKIV function. zCaMKIV and rCaMKIV differed in their substrate specificities, since rCaMKIV preferred histone H1 over myelin basic protein, while zCaMKIV did not. Moreover, zCaMKIV was more readily dephosphory-lated by zebrafish nuclear CaMK phosphatase (CaMKP-N) than rCaMKIV. These results suggest that the C-terminal region of CaMKIV plays a role in interacting with its target and modulator proteins
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.