Seizure-mediated accumulation of the β subunit of Ca2+/calmodulin-dependent protein kinase II in nuclei of mouse brain cells

Abstract We identified a 45-kDa protein by 2D electrophoresis that was enhanced following pentylenetetrazol (PTZ)-mediated seizures. Mass-spectrography of this protein revealed the β subunit of Ca 2+ /calmodulin-dependent protein kinase II (CaMKIIβ), although no evidence for increase in bulk CaMKIIβ transcripts was obtained. Physicochemical parameters of the 45-kDa species coincided with those of the type 7 isoform of CaMKIIβ, CaMKIIβ7. Reverse transcription-polymerase chain reaction revealed the existence of the CaMKIIβ7 transcript in the mouse brain, but its RNA content was small and was not elevated by PTZ injection. CaMKIIβ7 protein is thought to be accumulated in the nuclei of brain cells by PTZ-mediated seizure via some cellular mechanisms other than transcriptional and post-transcriptional regulation.