Different Localization of Tau Protein Kinase I/Glycogen Synthase Kinase-3β from Glycogen Synthase Kinase-3α in Cerebellum Mitochondria

We examined the subcellular distribution of two glycogen synthase kinase-3 (GSK-3) isoforms in rat cerebellum. Results from immunoelectron microscopy and subcellular fractionation revealed that one isoform, tau protein kinase I/GSK-3β (TPKI/GSK-3β), was present in mitochondria, but GSK-3α was not. Although the two GSK-3 isoforms seem to have similar properties, the difference of subcellular localization observed here suggests that TPKI/GSK-3β fulfills some specific function in mitochondria.