FIG. 1.

Enrichment of phosphorylated proteins by okadaic acid treatment of C. reinhardtii. Cells were either left untreated (−) or treated with 1.5 μM okadaic acid (+), as described in Materials and Methods, harvested, and used for preparation of a crude extract. Proteins (50 and 100 μg) were denatured in SDS sample buffer, resolved on a 9% SDS gel, transferred to a nitrocellulose membrane, and immunoblotted with antiphosphothreonine polyclonal antibody (Cell Signaling Technologies).