Calcium-dependent phosphorylation assays on recombinant PsaN, CAS, VAR1, VAR2, and GST protein. The two middle lanes of the left panel display the autoradiograph of ³²P-labelled proteins of a Ca²⁺-dependent phosphorylation assay of recombinant protein (prot) by an Arabidopsis chloroplast protein extract (chloro). The two left lanes are a control of protein only, whereas the two right lanes are a control for the background phosphorylation in the chloroplast protein extract. Note that GST is not being phosphorylated, instead a strong phosphorylation is visible in the EGTA sample of the chloroplast protein extract. The right panel is the protein loading control (CBB=Coomassie Brilliant Blue).