THE CA2+ CALMODULIN-DEPENDENT PROTEIN-KINASE II-ASSOCIATED PROTEIN COMPLEX ISOLATED FROM CHICKEN RETINA/

Retinal cytosolic Ca2+/calmodulin-dependent protein kinase II (CaM KII ) was isolated from hatched 6-wk chicken retinae by ultracentrifugatio n and affinity chromatography using calmodulin (CaM) and anti-CaM KII- alpha columns. Samples from different fractions were examined with SDS -polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining or immunoblotting. Comparisons were made between the final antibody affin ity eluates from retina and forebrain. Silver-stained gels showed that multiple proteins were present in the antibody affinity eluates from retina, including major proteins of 178, 56, and 45 kDa and several mi nor proteins. Immunoblots revealed that CaM KII-alpha was present in e luates from the retina and forebrain. CaM KII-beta was present in the antibody eluate from forebrain but not retina. The latter subunit was present in the crude homogenates of the retina. Regarding the antibody eluate from retina, the possibility that the major 56 kDa protein was tubulin was ruled out, but protein tau (tau) and synapsin I were pres ent. The presence of multiple proteins in the antibody affinity eluate indicates that these proteins were coisolated in a CaM KII-alpha-asso ciated protein complex. The finding that protein tau and synapsin I ar e associated with retinal CaM KII provides further insight into the me chanisms underlying the function of the kinase in this tissue. The lac k of cytosolic CaM KII-beta subunit in the antibody affinity eluate fr om retina is indicative of a brain region-specificity in subunit compo sition of the kinase.