Figure 5.

Phosphorylation of basonuclin peptide in vitro. Twenty-five micrograms of GST-SSS or GST alone was incubated at 25°C with 85 μg of keratinocyte extract protein in 100 μl of reaction mixture containing components necessary for protein kinase C activity and 1 μM okadaic acid. A 20-μl sample was withdrawn at intervals, the reaction was terminated, and the products were analyzed by SDS/PAGE (10% gel). Arrows indicate location of GST-SSS. Arrowheads indicate position of GST. (A) Time course of ³²P accumulation by autoradiography. (B) Proteins stained with Coomassie blue. (C) Plot of time course. Virtually no ³²P is incorporated into the GST alone. (D) A scheme of GST-SSS fusion protein.