Isoform differences in substrate recognition by glycogen synthase kinases 3alpha and 3beta in the phosphorylation of phosphatase inhibitor 2

An analysis of the phosphorylation of inhibitor 2, the regulatory subunit of the ATP-Mg-dependent protein phosphatase, by glycogen synthase kinase 3 (GSK-3), resulting in stimulation of the phosphatase, confirms major differences in substrate recognition by different isoforms of the same protein kinase. Substrate recognition by GSK-3 involves many determinants.