Differential subcellular distribution of Ca2+/calmodulin-dependent protein kinase II isoforms in the striatum and NG108-15 cells.
Four subunits of Ca2+/calmodulin-dependent protein kinase II (CaM KII) have several isoforms, which differ in the variable domain. We previously reported that all subunits were highly expressed in rat striatal neurons. To examine intracellular distributions of CaM KII subunits in the rat striatal neurons, we performed immunoblot analysis with antibodies specific to each subunit in cell extracts from the rat striatum after continuous sucrose density gradient fractionation. The alpha subunit, but not the beta, gamma, or delta subunits, was colocalized with synapsin I, and each subunit showed a distinct distribution pattern in the fractions. To examine further the intracellular distributions of CaM KII isoforms in the same subunit, we established NG108-15 cells stably expressing delta1, delta3, and delta4 isoforms and examined distributions of the delta and gamma isoforms in these cell lines after fractionation. Each of the overexpressed exogenous delta isoforms showed a distinct distribution pattern. The endogenous delta2 was colocalized with the overexpressed delta1, delta3, and delta4 isoforms. However, the endogenous gammaB/gammaC isoforms were not colocalized with the overexpressed delta isoforms. Furthermore, the endogenous delta1 was concentrated in the microsomal fraction from the rat striatum. With the results taken together, it is suggested that CaM KII forms oligomers between isoforms in the same subunit but not in different subunits. The variable domain of CaM KII isoforms might possibly be responsible for targeting to certain intracellular compartments.
Takeuchi
Yusuke
Y
Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki-Aoba-ku, Sendai 980-8578, Japan. yusuket@mail.pharm.tohoku.ac.jp
Nomura
Kazumi
K
Fukunaga
Kohji
K
D000595:Amino Acid Sequence; D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D003342:Corpus Striatum / Q000166:cytology / Q000201:enzymology*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology
D007527:Isoenzymes; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases