Figure 5.

DAH can be hyperphosphorylated by CKI. DAH protein was immunoprecipitated and the endogenous kinase associated with DAH was removed by 1 M KI (lanes 2–9). The DAH immunoprecipitates were then incubated with no kinases (−kin), or with casein kinase I (CK I), p34^cdc2/cyclin B protein kinase (cdc2), casein kinase II (CK II), cAMP-dependent protein kinase (PKA), PKC, glycogen synthase kinase 3 (GSK-3), and MAPK for kinase reactions (lanes 3–9). These samples were prepared for gel electrophoresis, followed by analysis with silver staining (lower panel) and autoradiography (upper panel). Casein kinase I hyperphosphorylates DAH protein, whereas the other kinases fail to generate a similar phosphorylation pattern as the endogenous kinase.