Immunohistochemical localization of Ca2+/calmodulin-dependent protein kinase type IV in the mature and developing rat retina.

The localization of Ca2+/calmodulin-dependent protein kinase IV (CaM kinase IV) in the mature and developing rat retina was examined by immunohistochemistry and in situ hybridization histochemistry. In immunoblotting analysis, a single band of 63 kDa was detected in the crude homogenate of the adult rat retina, indicating the presence of the alpha polypeptide of CaM kinase IV. In the adult rat retina, most of the bipolar cells and some ganglion cells exhibited CaM kinase IV-immunoreactivity. By immunoelectron microscopy, the immunoreactive product was predominantly localized to the nucleus of immunoreactive cells. In the developing rat retina, immunoreactive bipolar cells were first detected on postnatal day 10 (P10), and they were abundant on P14. All these findings suggest that CaM kinase IV may participate in some yet unknown nuclear Ca(2+)-relating visual signal-processing of the retina.